But it would look weird if she was there and heavily featured and the Chiefs weren't playing. This result makes it look much more "natural" which makes it easier for the public to accept and not question ("She's his gf, of course she's there! And if she just happened to endorse Biden/diminish Trump at or after being heavily featured on the most watched tv program of the year by far then that's just a coincidence!")

The point is that this introduces her to a mainstream American audience in the most "natural" way possible. Which then allows her to persuade the public throughout the rest of the year because we all will feel like we already "know" her. Plenty of people already "know" her, of course. But we don't need to reach those people. We need to reach the undecided and out of touch Americans in Michigan, Wisconsin, Pennsylvania, and Arizona - and we do that by using the Super Bowl as a political branding opportunity with our cleancut and All-American characters of Taylor Swift and her classy bf Travis Kelce.

It's pretty simple marketing/branding/persuasion. Not even the most complicated marketing effort that she herself has been involved in.