I'm not saying it is a courtroom, I'm saying if anyone had a problem with how Patreon operated (if they allowed "not-exactly-incest" content), Patreon could pretty much shrug it off without having to worry about public backlash, which is why I find this 'interesting': If Patreon was fully profit oriented, they'd likely just ask to remove/change incest content only (i.e. change "daughter" to "step-daughter"), they could allow "restoration patches" to circulate (strictly outside of Patreon), and as for public opinion, they could save face by stating "we do not allow incest, period".
If you are right and they can do pretty much whatever they want, then the only reason I can think of as to why they would nuke "not-incest" content is because of their personal preferences, which they seem to value more than profit.
Maybe removing actual incest *is* a good business decision, you are right about that, but entirely nuking everything that was or is, in any way, related to incest? It is most definitely not a decision that'll end in more profit or better reputation.
Not because "boo-hoo, we incest lovers can't have our fun", but because this decision says "whatever business you have, it is not safe on Patreon as they can just fuck you over on a whim".