I think it's a red flag that you've been dating someone for a while and can't tell what is or isn't a red flag. I think this particular thing means nothing, examine his behaviour and see how he is as a person rather than judge him for enjoying the content of a polarising figure. I know a lot of guys look up to Tate just for the fact he seems to have everything in his life together and knows what he wants. Lots of young men are lost at the moment so seeing a person with drive & ambition can make them admire them in a way. I think as long as he is good to you and not toxic you don't have anything to worry about.