Instinctively, I'd side with (gulp) 'Always Broken'. Talk of treason, shooting at dawn and latrine digging sounds like ignorant far right nonsense to me.
Had he refused to go to support the initial invasion, I'd line up with AT and RLE and would support the bloke's right to refuse to obey what he may have believed was an illegal order.
Except that he's a medic. Shouldn't he be going (like a WWI CE ambulance driver) whether the war was morally right or wrong? Isn't his part in ops always morally right (saving lives, looking after the health and welfare of his patients and comrades)? No-one's asking him to go and kill as part of an illegal war, after all.
And above all, I'd ask (as JtD asked more intelligently) what's illegal about the PRESENT, ongoing op.
There must be people here, from Kinloss, who know the bloke and who will know whether he's genuine but misguided, or is simply looking for an easy way out and a way to avoid unwelcome service in the sandy shi.thole.