A reasonable take, but I continue to think you're underrating (1) how important celebrity endorsements can be for driving turnout - especially a celebrity with the fan base and global recognition of Taylor Swift - and (2) how important a few thousands votes in some states are potentially going to be in this election given how thin the margins are.
I mean there's a reason the RNC gave prime speaking spots to doofuses like Hulk Hogan and Kid Rock. A lot of fairly low-to-moderate-information voters care more than you think about aping the behavior of famous celebrities that they support - athletes, musicians, entertainers, whatever - in the political arena.