"No dog in the fight", but you felt compelled to create a post on this forum... okay.
I coached against Plum, and I recall them having a pretty good team in the 19-20 season in Class AA. I don't remember what their record was, but I think they made the playoffs.
Varsity teams from small to mid sized programs will always have their peaks and valleys. If you are lucky, you get a few strong classes and you can compete for a few years. Sometimes that's not the case, and all you can do is maximize whatever the potential is for your team. If that potential is only a handful of wins, or hell - even no wins - then you still give your players, the team and the program everything you have. If this coach is doing that, then kudos to him, and he should stay put and Plum should be thankful he remains committed to them.