With slight modification small holding rooms are already on-board. Toilets, with a small mod to air flow. We know the perp (got it from the Bill) isn't carrying knives or screw-drivers to do any damage so, lock him in, squirt some appropriate non lethal sedative gas through a hole, and on you go. And don't say geting him in there is a problem. First of all he's pissed, and there are always a couple of ex squaddies, or similar, willing to help out.
Diverting a heavy aircraft because of one legless slob is ridiculous.