Hmm, yes, looking at it better, do we have any other Z-rated games in Smash? I know MGS, Bayonetta and P5 are M-rated in the west, but are they Z-rated in Japan? True, a RE stage without zombies and BOWs wouldn't really be a RE stage, would it?
I don't think it has to do with moveset potential unless Sakurai himself was dissatisfied - remember, the thing with Heihachi for example, it's not that he CAN'T translate to Smash, it's just that Sakurai wasn't satisfied with whatever he could come up with at the time and thus deemed it "too difficult" back then. He made similar arguments for Villager and Ridley and eventually made them anyway. So I'm not sure that would be too big of an issue.
Regardless, this could be an interesting development. and if the post was made (or at least archived) in February... then it makes sense that this was related to DLC planning, possibly CP5. So at this point we're either closer to getting Phoenix now or Dante's chances will ******* skyrocket in season 2.