This sort of helps to explain what sort of teacher Phil might actually be: the same sort of catastrophic failure Liz would become. Let's examine the most telling line in his Liography:
It didn't help his mood any that the incoming Grade 7 class was made up of the most fiendish lot of kids ever inflicted on a suffering world, with about as much music in the lot of them as in an average turnip. Their mothers were worse. The principal of the school was an idiot, always on his case grumping about discipline.
and translate it from "Angry, immature beatnik who should stick to teaching civics where he won't be a total embarrasmment" to "Sane human being."
For starters, the crack about the kids being fiends trying to torment him makes as much real-world sense as his ill-informed comment about how devious Mike is. Unlike him, we know that Mike isn't making it up when he feels as if he's joining the kid who drowned in the slurry pit in Apaches. We also know that Elly's "support" consists of making trumpet lessons feel less fun than the Bataan Death March. We even know what a condescending, intimidating, temperamental and demanding jackass Phil is when his temper flares up so it's obvious as all Hell that he'd decided to give up on the lot of them sight unseen because he was in a bad mood owing to the wedding planning that was going on at the same time making the poor baby-man feel like he was being ground up in Georgia's machine.
The part about how the children's parents were a blight on existence clearly sent from Hell to torment him is equally telling. As howtheduck tells us, it's vital to maintain good relations with the parents of your students if you want to have any sort of successful music program. Crapping all over them, mansplaining and treating them like nuisances because they didn't have his credentials seems to indicate that Phil had brought a Hell of a lot of his trouble on his own damned stupid, arrogant self.
To that end, so does randomly damning authority figures as being imbeciles because they blame him for his own dubious human resource management skills. What his whiny, self-justifying remark about how he's being tormented tells me is the same thing his vile and disgusting comment about Georgia being a schemer trying to unman him because his fragile male ego can't handle having to give instead of take says: we're dealing with an over-grown child who blames other people for the mess he makes when he's being a sulking asshole. It's sort of too bad that we're supposed to side with him and all the other alleged adults in this strip when they're so obviously in the wrong. More on that tomorrow.