Let me clarify: Richter will have the same mechanics as in the demo of the hack I released a few months ago. That means no high jump, no air slide, no brandish, and using frenzy whip will be possible, but have a delay between uses. He will also have his ground backflip. This is in stage zero only; his actually game will have all his moves and more.
As for why, that's simple: it makes the intro stage more retro and more difficult. 
Removing moves from a character is kind of a cheap way to make the game more difficult, but I dunno. I guess it doesn't really apply in this case, since doesn't
Richter basically have to learn all these moves in his mode anyway?
Also, about the backflip. Why the ground one? I think it should be the air one, since that's how it was in
RoB, also, it makes it easier to dodge things like, say, Hellfire.