As much as I hate to sound like a broken record...the M22's are simply too small for a room that size.
I too suggest putting them in a smaller room, to see if it's the "Axiom sound" he dislikes, or if it's only the fact that you're asking too much of the M22's in that particular room. If you move them into a smaller room, and like the sound, trade them in for the M60's or maybe even the M80's. That's a damn big room.
If it were my decision to make I'd return the M22's and put my subwoofer budget into a pair of M80ti's.
He can always enjoy the M80's without a sub, but he can't enjoy a great sub without great speakers.
Of course if he moves the M22's into a smaller room, and still hates them, send them back, and keep searching for some new speakers.
