Artisans, as is this hobby, is purely about preference. Can we agree to disagree on the necessity of a UV light? Yes, he might be missing out on some good UV reactive effects, does that change your appreciation of the hobby/your artisans? Is it necessary to make it that big a deal? Good lord...
Disclaimer: I do not own a UV light, might feel cute and get one later, I don't know. I'll do what I want.