Wow, lots of people here who do not understand at all how some wow guilds operate.
In a statement that will probably attract incredible ire from everyone here, i can vouch for the guildmaster if the guild was trying to compete in the raiding scene. Being in a guild isn't a right, it's a privilege, and if you're useless to the raid and the guild only does raiding, then you're useless to the guild. There is no reason for you to stay.
Hardcore raiding guilds in wow operate on a simple principle: finish raids faster than EVERYONE ELSE. Everything that hinders that progress will have no place in the guild. There's 25 people in the guild, they form one homogenous well-oiled machine or they die over and over. Being deaf in this case is a severe detriment to that part. I used to be in a guild that would have made the same choice: we weren't there to be nice to eachother and make like we were friends. We were there to raid, cooperate and reap the rewards; the bonding came from that last part. There's plenty of friendly guilds out there who are glorified chat channels, and none of them would kick him out on account that he's deaf.
As for text chat in raids: that's ignorant of how wow raids work. You have to be seriously crazy to use text chat in raids and expect to get anywhere. Ventrilo or some other VOIP channel is entirely mandatory due to the strict split-second decisions and the infernally fast pace once a fight starts. There is no time for standing around like an idiot and writing stuff down. Text chat means you die, it's too slow to save anyone, and it means people have one other area of the screen to pay attention to, which is BAD.
So if you were in that guildmaster's position, i DARE you to make the choice that would screw over 24 other people just for the sake of being nice to one of them, because, you know, it's a game. Even though you don't owe him a guild spot and he's made it quite clear that he will be a giant liability for the rest of his days. This kind of shit breaks guilds apart, guys. The guildmaster did the right choice, and doesn't deserve your scorn.