You could have just told me you didn't want it, and given it back. Harumph! Two hour painting class down the tubes!

What about at least input ,from him? Okay, it's less inconvenient for you to just buy the gift, but what does he suggest? What would be want to get? And are you really sure time is so tight, you can't spend an hour with him, shopping and maybe a fast food dinner?
Respectfully, he's an adult. Let him be an adult. If Christmas shopping doesn't work for him, next year he could remove himself from the gift exchange, maybe? Not buying gifts this year will likely have people rethinking gifting him in coming years.
Helped, sure.
Buy two
https://www.amazon.com/Pyle-Megapho...ild=1&keywords=Bullhorn&qid=1576279158&sr=8-4
If he shows up empty-handed, he simply doesn't participte. If people judge you because he doesn't wear a coat, "He's 16, old enough to make his own decisions. If you have an issue, please discuss it with my son, not me."
Help, sure. Done for them, not so much. At 16, or 25, or 48...