Stop in for a cup of coffee

Now here’s a question, could I not sand down the flat, outer edge of the center hub to let it clear as well?

Yes, I am sure you could. Lightly touch it with a grinder while spinning the hub the best you could, but @Ddaddy had a good point. Do it once on the rims if only for memory. Change rotors in a hurry some time, throw wheels on, run on with impact and go....ooops. Or if you sold it, kids end up with it, etc. If you had a way to spin the rim so you could run a buff/sand wheel in the pilot, it could turn out just fine. It is a tiny amount of material you need to remove. Just my 2¢