Most likely it's both. There is no question MANY are our enemies. Some are innocent and some are guilty. Sorting that out is a hard row to hoe no doubt. Assuming MOST of these yahoos are guilty and are our enemies, then what? Are they imprisoned for life with no trial? Are those who are innocent then also imprisoned for life?
It ain't the American way.
Given the data so far, most detainees are not and never were our enemies. We've released 3/4 of the Gitmo detainees so far because there was no real evidence against them. Of the remaining 250 or so, only 14 have ever been charged with anything. The government's credibility at this point is non-existent, by any reasonable measure. Of course, if you're 'in the biz' and earning a fat paycheck from Joe Sizpack working in the mostly scam national security industry that exploded after 911 (our only growth industry left at this point, as far as I can see), you're going to continue to maintain the party line no matter what.
There is no reason to believe that most the remaining detainees are guilty of anything more than being in the wrong place at the wrong time when some local bounty hunter, paid by the US to "go out and bring back some terrorists" kidnapped them to make some money, satisfy a personal vendetta, or both.