basically jonathan smith was going through all the characters who would be in the game including robin, batgirl and nightwing, and then praised the calibre of gotham villainy that they could choose from to put in the game. he went through a short list including the joker, catwoman and twoface, and said they were putting in as many of the weird and wonderful ones as possible. some kid in the front shouted out "man-bat!" and he said 'yes, man-bat, that's how low we're going', indicating that even the most obscure and rubbish of the rogue's gallery might get an appearance. which, considering lego star wars: the complete saga's huge character list (about 160), seems pretty likely to actually happen.
Source is a comment on joystiq.