It is not an end all, be all, class. The players he was facing were terrible and his team was dominating despite the kill streaks. One, its call a stinger, and you point the tube at the plane that is murdering everyone and it goes down. Next, the airport map is one of the few were nube tubes are that affective because there are relatively narrow 'hallways' and people cluster up.
Yes, the spawning is a bit hectic, but he is playing ground war which is pushing the limits of appropriate numbers of players in these maps. The game type is made for grenade spam and danger close.
I see the point the guy is trying to make with 'unlimited grenades'. Still, I've ran into plenty of players doing this and it is easily countered by some teamwork, stingers, sprinters, and flash grenades.