I get that his treatment upsets you and with good reason... however please bear in mind that in his OWN words:

"Peyton said he wanted to "live according to Sharia law." When asked to describe what that meant, he could only remember the rules that "non-Muslims must pay a tax to live in an Islamic land" and "that homosexual people are killed." He claimed to have read "eight chapters" of the Quran, but "I don't got any of it memorized."

So we have his own confirmation that he has a radicalised view of the world, agrees with some of the worst aspects of ISIS/radical islam, and lives in a country where access to deadly force is a constitutional right.

If the US authorities failed to act on this they would be held accountable for anything this troubled and damaged young man did.

So lets not rush to condemn the authorities here.... that's all I'm saying...