We will never know his intent.
However, IF you look at the position he is in in the picture that's floating around in this thread of the hit, his shoulder pads is supporting his helmet. The position of his arms indicate that he was using his shoulder pads by supporting his helmet and stabilizing his neck before impact. Its clear, however, that his intent seemed to have wanted to knock him out of bounds; tackling was not, he would have his arms in the 'bear hug' position if he wanted to tackle Nelson. Classic fundamentals of tackling, you know 101. Now going back to shoulder pads supporting his helmet sans neck. All indications point to a hit that was meant to cause devastating consequences. Whether it was conscious or sub conscious we won't know.
In any case Nelson is out and Arod will have to call State farm and file a claim.
Disclaimer: Devastating consequences does not mean he wanted Nelson out with a season/career ending injury. It means results that could be a dropped ball, caught out of bounds, etc to help the Giants and their "boot wearing on boat" crew.