Yes you're right. Neither side of the Crossover are canon whatsoever... I really should've told the dev of Lustful Sin to put a disclaimer that explicitly states that in his game but oh well. I made sure to add a disclaimer in my part of the crossover.
If it would make you feel better, I can ask him to add a disclaimer stating clearly that the Monroe and Kit that show up in Lustful Sin are NOT the same characters that appear in Dimension 69.
I hope that the reason behind all the downvotes I've been getting on my page recently haven't been due to these worries, if anyone had a problem with it I was more than happy to explain.
I said this in another comment but there is no NTR in Dimension 69, and there never will be. The crossover is just for funsies, if you don't like that sort of content, canon or not, then you don't have to play it. It's optional content.