People are still going to block people they don't like here, regardless of their xper level or if they're a moderator or whatever. I don't think having a certain status on here should make you exempt from being blocked. I can just see that being abused like hell. Senior members thinking they can act like dicks to people just because they can't be blocked.
That status is called being an admin. There are some users who have graduated from being an urban moderator to an admin. Being a moderator doesn't really have to do with how high is your xper level, but with your engagement with this site in general.
I think anyone of any level should be allowed to be blocked - All the higher levels means is you have more points - It does not imply that they give better answers - I am a master but I don't think I am capable of giving any better/worse answers than a level 1.