The hit itself didn't appear to be a dirty one, but as we've seen time and time again, when players see a teammate take a huge hit, especially from someone with a history of questionable hits, you don't leave anything to chance. Greenway endeared himself to Sabres fans by stepping up to have Power's back and I'm sure that Power appreciated the gesture.
Wilson was not penalized for the hit and both Greenway and Wilson earned the typical 5-minute fighting majors on the play. It was the Capitals, however, who got the last laugh in that one, skating away with a 4-3 OT win on home ice.