Juju lined him up and launched himself (shoulder and side of his helmet) into the face mask of Burfict. His immediate celebration pretty clearly indicates that he saw it coming, knew who it was, and delighted in lighting him up. It was premeditated and not at all a spontaneous act, though it was a football play.
Gronk's hit was equally vicious and was certainly later in the play, when he should have known not to do anything. It was arguably not even a football play. But it was also appeared to be his spontaneous reaction, out of frustration. He was certainly in the wrong and deserves a game. Juju was in the wrong for slightly different reasons (he went headhunting) and he also deserves a game.