Well, on the whole, he's right. I was also interested in this topic, because with the development of Patreon, there were a lot of works that actually use or parody other people's characters and at the same time commercialize these parodies, receiving money, in fact, for someone else's work.
I even contacted a guy who used to work in the editorial department of Shonen Jump and he said, literally -
"Basically, large publishing companies are usually aware of the availability of 18+ parodies and receive many messages from "zealous" fans about the misuse of content, but... even such an advertisement is still an advertisement. Parody porn games, one way or another, expand the recognition of the work and characters and, perhaps, can interest users who will then go and buy a novel, manga, or game. As long as the author of the porn game does not exceed the limits, such as cruel guro, outright pedophilia, with the participation of original characters, which can make the wrong impression, damage the reputation and alienate the fan community, the copyright holders can turn a blind eye to these violations. Moreover, the amount of money that the authors of the porn parody receive is simply nothing and the copyright holders lose practically nothing."
No wonder Fujino so aggressively mentioned that Yui is 21 years old.
So maybe Reki Kawahara himself is not aware of Fujino's game, but his agents or editors certainly know. And the fact that Fujino, as an emigrant, has not yet been thrown into the dirtiest and darkest prison may mean that his game has not damaged his reputation, and perhaps even brought new customers and a small increase in profits.
P.S. Although this formulation still leaves me at a loss. That is, the fact that Asuna became a cheating whore or Liz was brutally raped (which, to me, is pretty close to guro... but it's not for me to decide

) is not enough to affect the reputation of the work?