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.
Most users or website visitor or potential donators/supporters will read it as weird or something illogical IMO. As i said it does not matter if the coin came from exchanges or not, as well as nothing to worry about. Mentioning such thing will probably give potential donators to send you one from KYC exchanges since there's a little way to can tell if it came from where as donation.