I'm still a bit confused about this. I don't want to mix up my KYC and non-KYC coins.
Does this really matter? When you are just the receiving point? What's your concern about this aside from getting mix from KYC or not.
As long it's not from hacked platforms, malicious actors, or any kind of criminals, you're good.
If he wants to avoid receiving those donation from a KYC exchange, best way to avoid it is to specifically state it in his website. Let him write a warning telling visitors not to send him Bitcoin from a KYC exchange. It's as simple as ABC.