I guess this quickly slides into the realm of "conspiracy" ...
Here's something I've been thinking about lately: when the French Army was cut off in May/June 1940, an evacuation plan was put together at Dunkirk. Those who got out largely travelled to England by boat, then across England by train, and then were taken back to France by boat, with the presumption that they would continue to fight against the German Army. In order to buy into the Administration's ideas about this, you'd have to imagine people like Padilla would see jail time as a trip through England as above: they'd pop out on the other side, ready willing and able to continue their fight.
But yes yes, AlQ is not a country, and Padilla is not a uniformed soldier, and we don't have good rules about what to do about non-countries waging war with non-soldiers. Like I said before, I buy all those technical problems. And we certainly don't have good experience with US citizens fighting "on the other side" of such a "war" ... but I don't think it takes too much imagination to believe that this situation does in fact exist and does need to be dealt with in some reasonable way.
Remember that their underlying belief is: if we let him go, or even indict/try/convict of what we have (which might be minor at this point, except for 'conspiracy' which is hard to prove and hard to get a long sentence for), he'll be back. And we don't want him to come back. But we can't kick him out of the country, and there's no legal mechanism for dealing with him.
And this is a relatively new thing!
So again -- without just saying "it doesn't exist" and without applying it specifically to Padilla, because we really don't know what's up with him -- what is to be done about this very real (even if only potential) situation?
I don't want to get too corny about this, but imagine that the 9/11 plot was broken up before it actually was carried out, and it turned out that they were US cititizens. Given what we know about these guys now -- that their planning was long-term, that they (at least some of them) knew that the result of the plan was a suicide mission they firmly believed in, that in at least one case when a team member was denied access to the US he was replaced by another willing participant -- what would/should have been done, and what would be the outcome if they were tried on some conspiracy charges, jailed for a bit, got out, and planned and executed something else along those lines?
What do you do with people who are determined to commit a crime? Do we have to wait for them to actually do it before we act? Is it too much to expect that this kind of outlook is present in the world and that we should be looking for a solution to it? I said before: I do not like the currently proposed solution. But I do think it needs a good solution.
/jordan