The word isn't being misused, the MC lets another man fuck his wife while he watches. If that's not cuckoldry, then i don't know what is.
That does seem to be the case.
I assume you have access to regular porn sites.
I assume you can see there are definite categorisations that differ between swinging and cuckold content?
Do you notice how there is some overlap but that the bulk of the content of these categories is very much separated?
Why do you think that is?
Cuck dynamics have a flavour that is very distinct from swinging/sharing.
They are predicated on a forced element and, in many cases, on a component of humiliation.
Either the cuck or cuckquean is unaware of being cheated on or they are forced to endure it even if they fundamentally disagree with it happening... This is usually because of a position of inferiority. They may have a debt with the bull, the bull may have overpowered them physically or emotionally, the offending partner may have something on them (maybe just the threat of leving them).
More often than not, the offending partner is complicit in the affair, sex act, cheating, or at least gets off on it big time.
Optionally, but not at all infrequent IRL, the cuck is the instigating party, who gets off on the notion of their partner finding sexual gratification with others more than they get off from doing the deed themselves. In almost all cases, the cuck does not seek sexual gratification with others than the partner., prior or after the fact.
This is purely a one way street, often containing elements of humiliation, either imposed on or sought by the cuck, which can go all the way to becoming a sissy or a mere financial provider for the hotwife.
Now, with this in mind, try treating a swinger as a cuck, or using language with them or even their partner that indicates that's what you think about the situation... I can personally attest that that's the fastest way to get uninvited from many a swingers party or by anyone who might have considered to include you in their sexy times in a more private setting.
I've personally seen it happen that guys who came in with the wrong notion and didn't approach the situation with the right awareness of the differences at play were shown the door and banned from the premises.
Sure, there is overlap in the sexual acts themselves and the situations that can come to pass, but context is absolutely crucial in understanding the difference in approach, mind games, kinks at play, source and nature of the satisfaction and payoff...and to anybody involved in the situation, the difference is usually clear as day.
It's when the overlap and a lack of proper communication happen, and people aren't sure of their desires, that accidents happen and the game can get ruined, with all the potential fallout on the couple if they aren't on the same page mentally and emotionally. The net result is often retiring from "the scene" and going back to a monogamous couple life, a few scars richer. occasionally, the damage done and the imbalance are so severe that the couple implodes altogether.
The one thing that has been pointed out that I will concede, is that the game doesn't yet present a situation where MC is invited to enjoy another woman by the significant other of that woman, which might feel the approach towards that dynamic a bit unbalanced. I agree that the Queen passing around a slave is a poor representation of that idea, albeit conceptually the same.
This however is not the gotcha moment you might have thought it was. It simply means we haven't gotten around to it yet, as we were busy establishing the factions and getting the different missions rolling. The encounter at the Oasis could, in hindsight, have been a good moment to introduce that narrative, but that would have robbed Shani of het moment to shine.
I shall relinquish the soapbox now.