You shouldn’t have to. And he shouldn’t have to either.
What it all boils down is that he needs you as much as you need him. If you push aside all the nouns and make the verbs a bit more vague, it rolls into something like “You want his expertise and he wants to feel like he’s contributing and he means something somewhere to someone.” At some point his ego was stroked to validate the inner voice that Does No Wrong and now he truly feels that you all need him and he can do whatever he wants. The entire thing about him not caring is completely bunk because if he didn’t then he wouldn’t have to say it. He’d just leave and go on his own way.
If you remind him that if he truly does feel liberated by acting as he wishes, then why doesn’t he just do his own thing and leave the community? That questions the motives of his true reason for staying. “Why the hell am I here if I am unhappy enough to prod people like animals in a cage and get flack for it? Like they don’t appreciate what I’ve done the past ten years?”
Do that and he might just leave on his own without a word. If he stays then you have to tell him that the community doesn’t revolve around him, as @lee-dohm mentioned. If he truly wants to help others then he has to do it because he cares about the users and the community, not because he thinks he’s saving them from themselves and he’s the gift for you all. By that kind of basic logic his ‘liberating behavior’ is countering his attempts to help, if he truly is there to help. Again, by talking to him at this angle you force his ego to question itself and must react based on its own personal values and morals. This is the exact same self-talk I give myself when I feel the same as he probably does. Nowadays I don’t last ten years. I last a couple of months before suddenly disappearing as if I was never there in the first place.
Also, sometimes the holier-than-thou intellectual talk is natural. I know when I do it I truly am not attempting to downplay with big 5-dollar words and intricate, eloquent writing style. I have written constant stories (in RP) since 2001 and by now I’ve proofread dissertations. I’ve had the same situation as your user there where I get highly-positive comments on my writing ability and my constant outpouring of help for those who want to reach that level. I could have gone the route of your user there, if I allowed all that ego-stroking to become validation for who and what I am. But I didn’t, because I knew deep down people would suddenly look at me like you do to that user, in massive droves. My donated help and stories would be rendered moot. I might as well stop the attempt to go into communities or even make comments on the internet if I felt every single person was incapable of meeting my level of integrity and quality.
Sorry for the sudden text wall but this guy reminds me of myself if I went completely to the dark side, as it were. Nowadays the claims of ‘grandiosity’ and ‘intellect-throwing’ go in one ear and out the other for me because I have the ability to walk away before it turns into what you’re dealing with.