I've grouped with him 3 times so far, and he still always behaves like the weakest link. 

Tonight we group in a heroic Slave Pens group, and he mentions not needing Omen threatmeter because he has iceblock. Iceblock, as you all know, is the mage ability that makes it so you don't need to use a threatmeter. 

In tells to another group member, however, he proceeds to say that the reason he has to use iceblock is because I'm a crappy tank, and can't hold threat good. 

Said group member of course immediately spilled to me the treachery!

So, I'd say he doesn't make the cut. There's probably other guild members that think I'm a crappy tank that can't hold aggro, but they're not stupid enough to let it leak back to me.

Said group member would rather it didnt' get out that someone in the group leaked the information, since she doesn't want any dramatic tells from a vexed video game subscriber about letting it out of the bag. So don't try talking to him about it, or coaching him to be a better person! :)