Hmmm, the language and cultural cards? I've witnessed weaker cases have success. I think Renshaw should go for it...
Anyway, having engaged in a few bunch sprints myself, I would not want someone sprinting next to me at 60-65k thinking they'll be allowed to get away with head butting me to gain a few inches of space. With that put out there, you armchair experts that have never engaged in a bunch sprint at 60K+ - visualize for a moment and ask yourself if you'd be okay with another guy headbutting you at that speed...I didn't think so. Now consider what would be an appropriate punishment for that offender going upside your head with his at speeds that could be fatal...I rest my case...