I have to really wonder about your hatred for Johnson. He disagreed with the Enclave, but he still fought for it. "My country, right or wrong" and such. He married a local and tried to integrate only after the Enclave got it's collective ass kicked and bother their nation and their cause were effectively dead. By that point, he'd carried out his service oath and served well. Enlistment in the Army doesn't have a suicide clause, after all.
He served without serving. He stayed in the Enclave possibly as he was afraid to desert, or he knew about the Project and realized that if he quit, he would die as the FEV Curling-13 inoculation wouldn't reach him.
Arcade tells how Johnson whined constantly, picked fights with Moreno (who was, after all, their best trooper), whined some more and pretty much just screwed the rules as much as he could. He was actively campaigning against his country, which is a bad thing for a wartime soldier.
IMO, a true soldier follows his cause firm and quiet. No point getting yourself killed because of bad orders but constant whining, disobeying, dissent and the like hurt more others than it hurts you. If you don't like it, keep it to yourself. One bad trooper taints the whole squad. Moreno and Johnson hated each other. Were it not for their power armor, those two would have got them all killed very soon. And Johnson here is the one picking the fights, so I blame him.
But maybe my biggest beef with Johnson is his sudden arise of respect towards what he did. He suddenly falls into nostalgia about Sgt. Dornan and wishes that he could go "guns blazing" as they say. What the hell? You complained all the time, broke rules, and now you feel you're entitled to clear the name of those who you oh so vigilantly opposed? Stay in your cave, for all I care. Moreno does just fine without you.