<<National Guard, Air National Guard, and other reserve units all had deployments to Viet Nam during the war years. Not sure if every state had contributed, but they WERE deployed there.>>
Nothing's a sure thing. You can seek refuge from a flood on the roof of a house and then the house gets washed away. Whether the refuge worked for all who bought into it or not, the fact is that it was seen by Colin Powell and many others as a refuge for rich white boys seeking to avoid combat and in the case of G.W. Bush and tens of thousands of others, it fit the bill.
<<Soldiers aren't sent from the rear to the front unless they have the right MOS. No one wants a shitbird in their infantry unit if he doesn't know which end of his M16 to point at the enemy.>>
I am good friends with an AWOL U.S. corporal who was in precisely that position. He unknowingly pissed off a senior officer(the guy was wearing civvies at the time and was otherwise unknown to my friend) and late that same Friday afternoon, when it was too late for him to call around and find someone to countermand or otherwise nullify the order, an order came in for him to embark on 48 hrs. notice for Viet Nam, with all the necessary specifics included. My friend immediately packed his bags, drove straight to Detroit and over the border to Windsor. The guard at the gate of his camp knew where he was going and wished him luck. He got refugee status here and lived happily ever after as a Canadian. Maybe he wasn't going straight to the front line, but there was no reason not to think so. He was just as good a soldier as anyone else, and none of it is exactly rocket science. He sure as hell wouldn't have pointed the wrong end of the rifle at anyone.
During the war, my dad's cousin was an RCAF corporal in charge of a gun crew on a small island off the coast of Newfoundland. A 2nd Lt. dropped in on the island and told our cousin to arrest one of the crew for drunkenness. The order was absurd, our cousin refused to follow it and the officer threatened him with court-martial. The base commander dropped in on the island later to hear our cousin's version of the dispute. Almost immediately afterward, the Lt. was on his way to France.
The easiest way to deal with a fuck-up, or even with somebody who is just making unnecessary waves, is to transfer him out to somewhere else. Obviously, the Lt. wasn't necessarily going to the front, but his life expectancy sure wasn't increased when he got transferred from Newfoundland to France.