he owns copyrights to images if he has altered those and game texts and game name too.
No he doesn't but even if we want to pretend that any Renpy/Daz porn dev does it's literally not enforceable outside of *maybe* Patreon taking it down upon request. This idea that a developer can buy (or steal) pre-made assets and own their likeness is just not viable or realistic. Even if it was, again, find me a way to stop someone using them and a court to hear the case.
Moreover, who are they going to file an injunction, lawsuit or cease and desist against? Do they file it against "BonerMan69420" on F95ZONE? No, lol. Are they gonna subpoena F95 to release the info on the user that they don't have anyway? Good luck getting anything enforced on some dude behind a VPN in China or Russia, lol.
I said it a long time aho with the AWAM dev. Steal their shit and make it yourself. The issue there is the characters aren't just straight-up assets but slightly modified ones so getting a perfect copy of them is tough. Here? Most are just the assets you can get off Daz or any asset bootlegging site. Very little to no modifications I've seen.
Anyone or any group with the want-to can take any renpy game, unpack it, grab Daz, grab the assets, grab Renpy and take it over. Afraid Patreon will take it down? Don't use Patreon. Problem solved. This "they own the copyright" shit just isn't true or enforceable.
The ultimate truth is that most don't even wanna take it over because it involves work and 99.9% of people here are just here to jack off, not learn DAZ3D, Python, Renpy and other shit.