AoA already corrected so I will continue with the discussion. As was pointed out over at the Trillian forums AIM does generate revenue in the form of advertisement. Use Trillian and you cut that money maker out and why should AOL pay for us to talk for free online? Do you want to pay directly for the use of an IM? Hell no, neither do I, that is why I don't mind ads. Now as I said at Trillian, maybe if Trillian attempted to make a compromise and show ads for AOL only chat then they might be allowed on the AOL IM network.
BTW, I heard that Trillian .070 still works with AOL IMing. I read that it has to do with the encryption that AOL is bothered with in the newest versions, 0.71, 0.72, 0.721, and 0.722.