I agree that Fizzbuzz isn't a trick question or a brain teaser. If I disagree with you about "trivia", I think it's because I disagree what the word "trivia" means, not because I disagree about Fizzbuzz. Whatever.

However, I do meaningfully disagree about "variations of Fizzbuzz". It does make sense to vary fizzbuzz, if you suspect that your candidate will have literally memorized the solution, character for character. If that's a concern, though, trivial variations are sufficient: replace the 5 with a 7, or change the ELSE case from "print the number" to "print nothing", or something.

I agree that if your "variation" makes it "interesting", you're not doing Fizzbuzz.

Whether or not interesting programming puzzles are a good element of interviewing, well, there continues to be a wide range of opinions on that.