The way I look at what the NXT rookies did last night - is they chose a champion for Barrett to make his mark with. He won, they're following him now as the leader of their pack (wolves often turn to follow the strongest)... and they'll probably be around to attack SmackDown!'s champion (probably after Swagger). I don't think they had any involvement in the Taker situation, otherwise they'd have put Cena in a coma as well, and probably done it off camera. It doesn't tie the two attacks together at all, you're approaching from completely opposite ends of the spectrum in regards to how the attacks went and how they were carried out. If they had taken out one of the threats to Cena's title, fine... but that's not the case.
Kayfabe-wise, the two biggest dogs in the yard, sure... but that's the only connection, and I don't feel it carries enough weight to speculate that they're the ones who attacked Taker.