Probably because they were flying in international airspace and to "splash" them would be an act of war.
I could just see those Russian bomber pilots with their vodka bottles in one hand and controls on the other get the piss scared out of them by an F-22 doing a super cruise fly-by. The Russian would look down at his bottle, then over to his co-pilot who shrugs. He then glances back down at his bottle and tosses it over his shoulder.