To be fair, it's obvious the author is a non-native speaker. It's totally reasonable to miss the subtlety that a "cult classic" usually implies that it's not mainstream. Google doesn't even make that obvious in it first result: "something, typically a film or book, that is popular or fashionable among a particular group or section of society."

I don't really see how that hurts his credibility, since it's clear what happened and what the author meant. If your interpretation was that the author was trying to highlight his niche 90s sitcom tastes, then I think you were the one committing the communication error here.