It was an ugly hit. Whether it was delivered with malice, only Thornton knows. This is the kind of hit that can cripple if the targeted player (and Gill was lined up) is hit far enough away from the boards, unable to defend himself. His neck can be snapped like kindling.
Gill was less than a stride from the boards. Luckily, he took the force of the blow high to his body, but low enough that his neck did not hyperextend to a point of danger. No small bit of fortune. A little more space between Gill and the boards, a slightly more awkward tumble, and he might have left the ice on a stretcher.
......
That's not to glorify dangerous or reckless play. But if Thornton had been that engaged with his game, that ornery, that bold and fearsome, then there would have been no way for GM Mike O'Connell & Co. to deal him out of Dodge.