An incredibly valid reason.
I have followed a lot of projects.
One of the one universal constants is patreon dunking on any and all projects with p/c incest.
There are games on this website with like 600 subscribers that still had to expunge any trace of incest. Patreon's traditional and direct hard-assing is why DAZ renpy game #432104 uses "landlady" and "roomate" and depend on customizable relations to carry them to safety.
I don't think there's a single reasony anybody should even remotely chance their livelihood for no good reason.
TiTS used to attempt to toe the line, and then they got a stern talking to. This lead to substantial aspects of the frostwyrms being cut and multiple characte relations being rewritten or otherwise distanced. It was also the direct cause of that (ultimately failed) attempt from Fen/savco to slide from Patreon to Subscribestar.
Remember that? When they tried a haphazard attempt to shift from patreon to subscribestar (which didn't pan out) during that time when updates didn't even have the patreon link next to the update post? I remember. They (though I guess it's just B) play the game to the best of their abilities, but ultimately when the stakes are so high I don't blame them in the slightest for bending the knee.
I don't think this in particular is a complaint that I think is fair. CoC was funded in an extremely different landscape.
Edit: Goodness. Let's try and fix this post.