Hey, I wonder if suggesting (or convincing) him to clear up hair back there might make him feel more ‘clean’ and comfortable with you eating his ass? It doesn’t sound like it matters much to you which is great, but might help him feel less self-conscious! Especially around the hole itself - shaving carefully, hair removal cream, etc. Also if he’d let you, you could always offer to help him do that as it obviously will be a bit harder for him to see back there himself.

Wife and I aren’t personally into eating either’s ass (at least not yet!) but I myself prefer how my hole and all looks back there when the hair is cleaned up and trimmed or shaved! She doesn’t care about it much for pegging me and all, I probably care more and feel better about it. I shave/trim around the hole myself by squatting over a small-ish mirror to see it myself.