What's the deal with Tazgar in the Temple of Sol Ro?
 

You lose faction simply by hailing him?

What's his story? Is he connected to quests? The wiki has nothing

I think it's just a generic "How dare you address me as I am so above your station," kind of thing.

He's like an angry librarian. I wouldn't hail him anymore as it's a substantial faction hit.
check out the rants section about him at http://everquest.allakhazam.com/db/npc.html?id=3301

That's what it is. I don't think he's for anything useful.

He's always been like that, no apparent use other than flavor - ie how dare you address me as above posters stated.