For me, the problem is that this is a pathetic jab at Kas. I don't think Kas gives half an ounce of a fuck about Quin or you.
I think this paragraph would make for some interesting discussion tbh
There are instances when the champion, the one in relationship with her, just throws in a quick jab at Kas. I think if you give birth to Brints children there is one that paints Kas as a villain that must be stopped. Not even alluding to fact if your champion is into her or not. It is just authors writing in the moment and I always chalk up to it our champion just thinking what is on their mind. Not really justifying it here, just my take.
At same time, I do not find this one grating, so to speak. I think it only really suffers from using the world cucked. Maybe jealous would be more appropriate and/or less childish. Since the way I read it is:
a) If your champion dislikes Kas, you would be kind of glad/amused by the prospect of Kas being bitter that she was directly throwing herself at you, and here you are just throwing yourself into the arms of a assholish bunny boy and wanting her dead.
b)Lovers of Kas can perceive this as the champion saying how jealous Kas would be that you, her lover, are showing equal amount of affectiong torwards the jerk ass bunny.
Now, that said, you could argue that this is maybe informing to much of emotional connection between Quinn and the champion without players input. As in, it is equaling the relationship between you and Kas and you and the rape boy as equal. This is all in eyes of beholder after all, since some players may seem one greater then the other or they value both equally. Now, a writer usually has no way to gauge the players interest in the character or they have no desire to. Barely any NPC has a relationship gauge (even Kas, the one you pursue, can either be your enemy or lover, nothing in between). So they can just write one type of dialogue. But than again in case of Quinn, who has one baked into his code (you can be his acquaintance,friend,lover) probably could account for it in some way.
But at same time, mentioning others NPCs is pretty pointless in my opinion because accounting for all those variables is more pain than it is worth. Well, usually. So maybe Bubsy should have just not bothered with mentioning Kas to begin with.