Principal MacIntyre is portrayed by Dave Foley.
Principal MacIntyre later fires both of them for taking Dee's class to a screening of Lethal Weapon 5 at Paddy's Pub. It's implied his poor judgment in hiring them will cost him his own job in the near future. ("Dee Reynolds: Shaping America's Youth")
It turns out Principal MacIntyre was not fired over the "Lethal Weapon 5" debacle, but only because he's got tenure and can't be fired. He is, instead, transferred to a middle school, where he crosses paths with Charlie and Mac again when they offer to protect the school from shooters. He later has to ban them from the school grounds after, as part of their effort to provide "security", Charlie and Mac threaten various students with a sword and a gun, and "confiscate" (i.e. steal) the cell phones of a few others. ("Gun Fever Too: Still Hot")