I don't think it matters that he led with his head, they made these types of blocks illegal a couple years ago thanks to Hines Ward.
"The blocking rule makes illegal a blindside block if it comes from the blocker's helmet, forearm or shoulder and lands to the head or neck area of the defender. One of the highlights the NFL competition committee used to portray such a block was the one Ward threw last season that broke the jaw of Cincinnati rookie linebacker Keith Rivers."
Read more: http://www.post-gazette.com/stories/local/breaking/nfl-approves-hines-ward-rule-335030/#ixzz270z6Ptor