After all the fuss they did need to put on a bit of a show. How would it have looked if they walked him off a 330 with a couple of suits on either side. Doesn't exactly justify his 5 years without trial and dangerous freak status if he's treated like a normal crim.
I think Hicks should have stayed in Australia rather than venturing off on his Jihad adventures. He could have been a Nominee for an Outlaw Motorcycle Gang. He'd still be in jail and it would have been cheaper, would've suited his living on the edge dreams too.