As much as I'm conflicted about using what's clearly akabur's art to either train or configure this AI, I have to say that having more of "his work" to enjoy feels nice.
Maybe what i'm going to write here is controversial but i'll use your comment to give my take about this matter because i see this a recurring topic/criticism (and will be even more recurring in future, we are entering into AI age afterall).
I don't really see where is the problem: Akabur's work were used to train the AI but i like the art of this game and judge it more an evolution of original instead of a bad copy of it, that can only be a good thing in the same way that an old movie AI upscaled can be better than the original format.
I could agree on these doubts if the dev was trying to hide the fact this game uses AI art trying to deceive us into thinking that was drawn totally by himself but he was quite frank about that so i don't have any problem if he uses Akabur style or whichever else.
Of course if he would be a true gentleman could write somewhere in the game something like "thanks master Akabur for the inspiration to make this game" or something like that but tbh it's totally up to him and even if he doesn't i wouldn't judge that bad because in a way or another Akabur one came first and will always be aknowledged as the "original one".
All in all Akabur made a lot of great games and sometime in the future somebody else will improve them in art and gameplay, it's only natural. This could be the right project or not, only time will tell us.