I was freaked out about the air travel thing, until I had to travel for work during the summer. Then I realized that it's a pain in the ass, but you are less likely to get sick on an airplane today than you were 2 years ago, because everyone is wearing their masks, and at least on United, they are serious about it. They even give you a wipe that you can double wipe all the crap they cleaned before you got on. I've flown to Mexico, to Seattle, to Boston, to Chicago and will be flying to Europe and a couple more work trips between now and the end of the year.
I did come home sick from my first work trip, but not COVID, just picked up a cold from being out at restaurants and bars with coworkers and not getting enough sleep for a week after not exposing my immune system to anything at all for a year and a half. He'll be fine. You'd be fine too, pay for the upgrade to premium economy, so you'll be around the people that are more used to traveling in this, and you'll find it's a pretty pleasant experience.