He certainly is...

http://www.thottbot.com/q10261

Hope this info helps..

I know that he has caved me several times (67 feral druid), although I bring him to around 12% health using the small amount of stunlock available to us feral druids...eg...pounce -> shred -> maim -> mangle (cat) -> shift to nelf -> rejuv -> lifebloom -> shift to bear -> bash -> spam lacerate and mangle (bear)

he is one tough cookie, so the quest line to kill him won't be one I rush out to start