This isn't the first time this situation has come up - that a successor has brought his predecessor's supporters up on criminal charges. Let me remind you of one singular case:
After Henry VII ascended the English throne at the Battle of Bosworth in 1485, he set the date of the start of his reign earlier than the battle and threatened the supporters of the defeated Richard III with treason. Men who had defended the "rightful" king were being accused of offences against the usurping king. (from BBC News)After some back-and-forthing, Henry VII capitulated, and the men were released. How does this apply today?
Those who give their loyalty and advice to the previous ruler may not be prosecuted for those actions. That, in essence, is what the lawyers who were asked their opinion about torture were doing - giving their legal opinion. They may NOT be prosecuted, even if that advice was in error.
Obama's supporters want to see heads roll - they are Madame Defarge and her allies, eager to see the "enemies of the people" led to the guillotine. Obama has put the CIA and the military off-limits to prosecution. He had to give the mob SOMEONE - he chose the lawyers as the ones who would be least liked.