I can only hope that if they do get done with the game that it will be in good taste. (Aside from the name) still not sure if he is gonna try and teach people about doujin in his story mode, and I pray he leaves us out of it.
If they are going to make the game educationnal about what doujin culture is, then it becomes pretty hard to picture how things'll turn out. There are educational games that are legitimately good, but some are fairly awkward. The only other game that uses the mechanics of another game and tries to be educationnal (like in their case, I presume) that first comes to my mind would be an m&m's (?!) game that-somehow-involves-mathematics (?!!!!) of questionable quality (
see for yourself) : it's... weird. To be honest, I can't picture how they'll make a fighting game that is also educationnal, especially if it's about a theme they misunderstood. I'm not gonna say it'll turn good or bad, I ain't no prophet, but there are seriously better options than this IMO. I'm still curious about how it'll turn out, though.
Isn't there something law-like for slander if its in a game that's pretty clear who it is?
Not sure if I understood your question or not, but long thing short, there are no problems with references, parodies, "hommages" and the likes : They are pretty much making Sakuyas out of Dio Brandos here (bear with this until you get a technical answer from someone else). And as far as the use of characters from other franchises go, quite frankly, if they get into some trouble again we don't have to get involved, it'll be their own problem.