Obama's incoherence on terrorist detainee policy

If you are going to take a purely legalistic position on people, the Obama position is clearly illegal.

If the applicable law permits us to hold dangerous detainees indefinitely without trial, then we should hold all such detainees in this manner. After all, we cannot be sure in advance of a trial that we will succeed in convicting any particular detainee.

And if the law does not permit us to hold dangerous detainees indefinitely without a trial, then I don't see how we can decline to try a dangerous detainee on the grounds that our evidence isn't good enough to convict. Rather, as Jameel Jaffer of the ACLU says, "if they cannot be convicted, then you release them; that's what it means to have a justice system."

In this scenario, wouldn't Obama be acting in clear disregard of the law if he picks which detainees to try based on the likelihood of obtaining a conviction? And wouldn't he and those advising him be subject, potentially, to prosecution in the event that the law is found to require trials for all detainees?