This is interesting. Your first two assessments are pretty spot on which begs the question of why Jacques is an option at all. I didn't choose him either and didn't see much benefit to an alliance with him so I do wonder what playstyle or story path he is meant to signify. Maybe someone who is playing neither "good" (trying to undermine the twins) or "evil" (trying to overthrow or replace the twins) but rather someone who is fully resigned to being a slave of the twins. Even in-game Rowan makes the assessment that he is the last person he should pick. So what effect could choosing him have long term? It has to be something deeper than just having another gay love interest I'm sure.
Jezera explicitly recommends Rowan to side with Patricia and corrupt her using the magic necklace. Upon doing so, Rowan discovers that Patricia starts being completely loyal to her new mistress and doesn't even care that Rastedel is half-destroyed and sacked. That's why I think this is the route for someone who plays Rowan as a "slave to the Twins".
I agree with you that Jacques' route is meant to signify a certain playstyle or storyline, but right now it's very ambiguous what could become of it in later parts of the game. I suppose there will be more to his character in Act 2 (provided he lives), especially since his wife was introduced with a separate sprite. When we look on what each faction in Rastedel signifies, it's very obvious that:
* Werden stands for the current establishment made of nobility and clergy - he doesn't desire more influence than he already has, while possessing a strong power-base in the form of his own duchy outside of Rastedel (which makes him completely independent);
* Jacques represents the city's bourgeoise, mostly made of wealthy merchants - he is ambitious but also very careful; he is independent only to a degree;
* Patricia doesn't align herself with any major faction and tries to fulfill her own political ambitions while not possessing all the means to do so (which makes her the perfect puppet for Jezera/evil Rowan, who can use her hunger for power to control her effectively).
Out of these three options, evil Rowan obviously picks the third one, but which one should be picked by the good/neutral Rowan? If he is truly good (in the most obvious sense, supporting Solansia's order, etc.), he should side with Werden, because that option provides the only possibility of returning to
status quo ante bellum after the Twins are defeated. If you choose Jacques, it's clearly stated that he doesn't trust Jezera - he only agrees to serve her because it's the best course of action for him at that very moment. If the Twins were to become weaker, he would probably betray them. Maybe the Jacques' route has been added to give Rowan another option outside of being evil/supporting Kharos and being good/supporting Solansia. Jacques serves neither of these powers. His greatest political wish is to create a republican system, of which the bourgeoise, including himself, would be the
de facto oligarchical rulers. If Rowan isn't corrupted, but also holds a grudge toward Solansia and nobility, he could potentially agree with this ideal.
Jacques' route provides with some unique potential story-wise for the next arcs. Siding with him is certainly an interesting choice, but as an ally, Jacques is very shaky and not trustworthy, both for Rowan and the Twins. That's why I don't think it's a good choice.
