My own opinion is that he knew what the evidence was - lacking, etc - and decided he'd make it the next guy's problem. he let a bice chunk of gitmo bad guys go, and many of them did return to attack us.
I guess, like Obama making his healthcare plan start in 2013, it was easier to do the gung-ho battlefield stuff, but making a legal case was going to be harder.
Hell, maybe there isn't enough evidence against these guys to try them in a military tribunal, and they know it - so they're trying them in NYC so that they'll be convicted and hung on emotion alone. Wouldn't that be a MFer lol... what if Obama knows this and is taking all this heat, because they have no case in a military trial.