Thousands of extremely dangerous thugs with no ideology will make an undisciplined mob. 19 extremely dangerous thugs with an ideology can change the world.
Once on American soil the folks from Gitmo have all of the rights of the accused common criminal. Putting ideological thugs into the general prison population of a supermax prison will result in radicalization of some proportion of the inmates. Some proportion of them will eventually go back into the general prison population -- in the legal system, it is the norm to encourage parole.
I don't believe there is parole in the Federal Prison System for prisoners incarcerated after 1987.
To the bigger question, while there is obvious cross pollination issues if prisoners are included in general population the Federal System, according to my cuz the US Marshall who deals with this crap says they have more than enough ways to address that issue.
To the bigger, bigger question, your line of thinking suggests that, if we can't process them here and can't send them to their home countries, that we have, in effect given them a life sentence without parole when some have not done anything beyond be extreme zealots on foreign soil.
Cheney says they are really really bad guys, Military says they are bad, CIA says they are bad. That may be a fair assessment of their "badness". We are convicting them for what they "might" do, not what they have done. Somehow that seems against our code of ethics and morals.
There are some very odd contradictions that are involved in the whole Gitmo issue that folks don't seem to want or like to face. The polarization, as you say is too great.
At what point do we, as a country become America again?
When do we look around, look at the good, the bad and the ugly and say to our collective consciousness that we want to be the best we can be at EVERY level, that we don't want to compromise integrity, morals or ethics to cut corners, to feel safe today at the expense of precedence setting changes to our moral fiber that can last for every and exacerbate at every new compromise?