I think the actual quote was something like "I cannot fit any more Darkstalkers into the game than I already have" in response to some of the tweets for characters like Talbain. Somehow people turned that into "there won't be a third Darkstalkers character in the game".
Basically, if someone thinks Niitsuma lied, it was either:
1) An obligatory lie, such as why he couldn't tell us at the time why The Human Torch wasn't in the game.
2) A faux explanatory lie because fans want "reasons" for their characters not being in.
3) Someone misreading his statements.
He's never outright lied, though, as far as I know. By that, I mean he has never said "X is true" when X is false.