He leads with his head. If they're going to be calling that, regardless of whether or not there's contact, it looks like a clear penalty to me. You're supposed to see what you're tackling because it's safer and makes it harder to miss the tackle as well. This guy isn't doing that and is clearly leading with the crown of his helmet. I don't have a beef with this call as the rule currently stands.
I don't have any particular issue with the spirit of the rule. It will force players all down the development pipeline that you should never, under any circumstance, duck your head when tackling someone. The problem, as with all things NFL, will be with the implementation; especially in edge cases.