Like others have suggested, it shouldn't be a problem IF it was regularly serviced and well taken care of. However, unless it's a screaming deal or the only 900 in your neck of the woods, I'm not sure why you'd buy it. There're plenty of low-mileage 900s around for sale, including brand-new, zero-mile dealer overstocks that can be bought at great bargains. If things are different where you are, though, that of course changes things, and perhaps makes 22K miles look more appealing.
( Used to have: )
'08 Vulcan 900 Custom:
*Passion Red *Mustang One-Piece Vintage Seat
*Hard-Krome 2.5" Strippers with Smartpartz Hard Kore Baffles
*Cobra Short Sissybar, Pad & Insert *Leatherworks 312 Chopper Bag *Small/Med. Windshield