You can add NIP05 easily to any domain you have access to. Are you filtering only certain domains? I have my personal domain for NIP-05. I could add any npub to it and it’s not “verified”.
If you added npub's that propagate spam, s*** coins, and p*** to your domain I would probably save myself the trouble and just mute the whole thing. And if I was operating a relay I probably would do the same on that level. Especially if the aim is to be useful.