anti
oppositional
the one-line answer
Someone who actively dislikes a celebrity or character and organizes opposition.
An anti is the opposite of a stan. Where a stan defends and promotes, an anti tracks and criticizes. Anti accounts exist specifically to counter a celebrity's positive coverage.
mainstream
Your coworker might use this word.
01 / in the wild
hear it move.
fandom
the antis were out in force after that interview.
People who actively oppose this celebrity were very active after the interview.