Understandable. Although vaccinations have proven only partially effective at preventing you getting covid so even if he was vaccinated you wouldn’t be in a much better position in that regard.
You might be right, but we’re erring on the side of caution. There are many things we can’t control so we’re focusing on the things we can.
I don't know what the parent of your comment is talking about. Vaccination shots 6+ months ago are not that effective any more, but if you got a booster shot recently, it's very effective. It reduces your chances of getting COVID by a factor of 5 to 10.