Why the Dragoons are not retarded in leadership

I am the GM of a 10 man raiding guild.

I had a problem child in my guild up until last night. A little background on him: Back in May, we were still doing Naxx runs to get geared up and we had 11 people RSVP. I didn't have room for a player we will call X, and i told him so. He refused to come to any raids that I've run until now, because "THAT GM IS MEAN"

I don't give a fucking shit what you think, so you think I'm mean? And refuse to come? Taking a stand for yourself, going over leadership? KICKED!

He wears PVP gear to raids and refuses to switch it, even when I tell him there's better gear out there. He won't talk directly to me, he will only talk to my officer, who is his friend in IRL. We recently lost a melee DPS (last week) so at a guild meeting, I told people to keep their ears to the ground for one. He got REALLY pissed at this and almost quit (he is a melee dps), because he thought we were discounting him as a raider. He can't even raid all the days we raid...so obviously, we do need to recruit people to fill in ALL the days.

You wear gear and refuse to switch? KICKED! Wont even talk directly to me, oh oh oh KICKED! Complained like a bitch, FUCKING TOLD LIKE ONE AND KICKED!


Anyway,

So, last night, my guild and I were doing a Yogg run (and unfortunately we didn't down him. Still working on it though!). 11 guildies RSVP'd, and obviously I had to kick someone. I left the person who just got back from a loooong hiatus from the game, because he had not helped us get to this point. I sent him a tell along the lines of:

"Hi, X. Unfortunately, we don't have room in our group tonight for you. I want to continue to try Yogg with the group that has gotten us to this point. Thanks for being on and we'll see you at future raids."

No response. This is 10 minutes before raid time. Before raid time, I am typically in tell hell, so when he didn't respond I didn't think anything of it (often, people DON'T respond when I send them that message). One of my officers is IRL friends with this guy, and she says in Officer chat, "Why did no one tell X that he isn't invited tonight?!"

Didn't respond? Kicked from vent, starts bitching, told off.

Except, I did. He missed the tell and was ranting about it 20 minutes later, when it obviously wouldn't be in his chat log anymore. He accuses me of lying to him, etc etc.

TOLD AND KICKED

Last night, we actually managed to find a melee DPS to join our guild, and he did (he's a friend I've played with in game for awhile). Once my friend joined, X /gquit and sent me a tell saying, "I'm too old for this !@%#. This guild has bad leadership and bad people."

I told him good luck.

Finally did right thing.

Now, when someone gquits like this, how should I address it? Obviously I don't want to play the "pointing fingers game", but I feel like I should acknowledge that something happened. I don't want to bad mouth this person in G chat and seem petty, AS MUCH AS I WANT TO.