It's already been stated that he'll likely never get out.
As Moose says, it's a moral choice, you have to draw the line somewhere. If it means maying a negligible amount more tax to live by those standards then so be it. I daresay it would be cheaper to stop collecting and processing our domestic refuse, but I'm happy to pay towards a society that considers itself above living in its own shit.
So would cutting off his arms and legs, poking out his eyes and sewing his mouth shut. It would certainly be cheaper than detaining him. But we don't because we are above that.
Trained, yes, but on Earth and on the ISS. No-one can entirely predict whether that'll be enough when you're 400 million miles and 6 months away from not just home, but anything that won't kill you if you step outside.
Not sure what it's like in other countries, but here you'd probably get away with killing someone if you can prove your life was in immediate danger. This is the only time I could ever justify killing someone - if, personally, at that moment it was either you (or someone with you) or them.
This is entirely different from seeing someone in your yard and coming out guns a-blazing. Tony Martin* take note.
*Shot a teenager in the back and then claimed 'self defence'
A lot of the problem is radiation shielding as once you leave earth there's no magnetic field protecting you from the solar wind. Although it would be easy to just wrap the ship in lead plating, the problem is then getting the now very-heavy spaceship into orbit in the first place.
There's also the psychological effects of being in a cramped habitat with 4 or 5 other people for a year or so - it would take 6 months just to get there.
Holy crap the test build is amazing. It looks GORGEOUS, and not just new lighting - new textures, and they've not just 'dressed' the old maps, they seem to have upped the resolution of the heightmap as well as add LOADS more fidelity and natural undulation to the ground - no more fields that could be a LFS circuit... They also have realised that people will want to climb all over the maps like mountain goats - there are lots more sneaky places that are accessable to the more nimble tanks who are prepeared to experiment.
As for physics -anyone with a T-50-2 is in for a treat