It would be selfish of Rowan and absolutely as far from heroic as he could be, but to me it doesn't sound impossible that a bargain could be struck where he will help the Twins conquer the world as long as he is allowed to have his own "little private piece of heaven".
It is possible but, think as the twins... Why would they do that?. Think about slavery... Why a master must grant something to a person that is in a literal sense their property?. The slave itself must be grateful of not being treated as a whore, punished or killed by the masters opinion of how the slave is doing the work.
My point is that this would be more of an alternative branch of the "Submissive Rowan" route, where he is obedient and loyal to the Twins, but instead of it being about he getting dommed by them and corrupted into being a masochist that enjoys being abused and humiliated by the Twins, we reach a state where while he will never see the world the way the Twins see it, he also doesn't find it worthwhile to plot for their downfall (too much personal risk), so instead, as long as they can assure him that he will be allowed to have a comfortable life where he and his loved ones will be left in peace without being harassed for not vibing with the whole chaos lifestyle, then he will work for them without a hidden agenda.
The twins can said to him that, but still... They are The Masters and Rowan just a slave at the end of the day, this bring to me memories about the Bible, do you know about Joseph?... They guy who was sell as a slave by his brothers and then was bought in Egypt, there his Master recognize his skills because he was very educated and could do administrative work for good, but his wife wanted other kind of services from him... And even when it was proved that he didn't do anything wrong to his Master he was put in jail anyway... That's the life of a slave. The twins have his life and of his wife in their hands... And besides that, the lives of many innocents villagers of all the towns conquered or under their protection; not only that, the twins state to him that if he cannot achieve the high bar they put to him to accomplish in a mission, they'll do what they pleased as in Rastedel... Those are motivation enough to be submissive or be rebellious... It's up to that player choice.
While I think the more nuanced discussion of the merits of "order" and "chaos" without dumbing it down to valuative terms like "good" or "evil" is interesting from a theoretical aspect, I think that as of how it applies to the SoC world there is not much room for ambivalence.
It would be interesting to delve into how the philosophy of "Chaos" works in the SoC world, like you said, it seems that it attracts people that are simply looking to fulfill their baser desires, but I wonder if that isn't also part of the philosophy of chaos, I wonder if they consider baser desires to be the ones that are most true to oneself and denying those in favor of "moral satisfaction" goes against the logic of "might makes right", because you are essentially surrendering your true self to the rule of a moral order.
I believe that depends in how it is focused... There is not much to opt, i mean, an static order as could be the Feudalism sucks a lot, specially if the rulers commit the most retarded decisions they have the right of it just because they have the luck to be born in the right place at the right time... While Might Makes Right oriented to Chaos can do more interesting things because the attractiveness is the Freedom it have to the follower, someone as enslaved as Rowan is could appreciate this, in fact, he does when talking to his wife he hopes for the twins doing it right, for Rowan that philosophy is overextended beyond the use of brutal force, and Rowan in-game demonstrate it when a mercenary wanted to go home in a village with problems to raised productivity. The man said he was a farmer and knows well how to make to produce the land because it's familiar with it and with the knowledge to do it, but an orc state the man is greedy because by the rules of conquest he was the first in put a foot there so the village is now his property.
Rowan can make a decision, to favor the orc or the mercenary, if he choose the orc Might Makes Right, the orc and the mercenary battles for the village, but after a brief time the orc strength surpass the mercenary and Rowan said to the orc to be sure the village productivity must raise. In the other option the man leaves to the village with the promise to achieve the rise of productivity, the orc complains but Rowan said if he indeed violate his rights as a conquer then Might Makes Right, he can opt to the twins because they put Rowan in that place of Power or he can deal with Rowan personally, is up to the orc, the orc shits and learn. So Rowan in this example of Might Makes Right he have the freedom to goes by Force or by Meritocracy, because if the orc couldn't accomplish to maintain or rise the productivity, then he's not qualified to get shit done, so, at the end, we can assume the village could get in a better state thanks to Rowan decision to put a person that came from it and knows well the land and was a farmer before mercenary, plus the village now is more loyal to the twins... Now think how the orc could achieve that, he could only order by menacing them, the orcs in the entire game only steals what they need so, in that village the orc just rule by fear until they get dead by exhaustive work or something worse (like famine or sickness like covid or something like that).
Another example of Might Makes Right is every time the game put the player in the opt to conquer or trade a village, we can perfectly burn, stole , rape, enslave the men to the mines, enslave the women to be breed by creatures in the breeding pits, their kids enslave in the castle as servants to be corrupted and the babies to serve as food for the beast in the castle. But don't, we can perfectly trade with them... There is nothing more chaotic than The Market itself when isn't regulated, but still the more free is The Market the more wealth for everyone in society, pretty curiously for the believers in The Order, as i state before, The Chaos have it's own Order by harmonization of the entities in it, and by Might Makes Right we always have the choice at hand, We Can one thing or another.