Again, the helmet to helmet wasn't the pronlem. It was LEADING W/ THE HELMET. I thought you were talking about Smith, I haven't been paying attention to what they said of the Welker hit.
It's a really tricky situation, because he had to lunge towards the receiver to even have a chance at the play which you know is pretty damn near impossible not to lead with your helmet from that angle. Rhodes just happened to make it so it was an obvious illegal hit. Unlucky, but I wouldn't have wanted Smith to do anything differently.
Anything could be called as "leading with your helmet" then... that is the way tackles are made... you "launch yourself like a rocket" at the opponent in hopes of stopping them from carrying the ball over the goal line.