Helmetless Motorcyclist Killed While Riding to Overturn Helmet Law

From the (Syracuse) Post-Standard:

A Parish man who was participating in a motorcycle helmet protest ride was killed this afternoon when he went over the handlebars of his motorcycle and injured his head on the pavement, state police said.
Philip A. Contos, 55, of 45 East St., Parish, was not wearing a helmet while driving a 1983 Harley Davidson motorcycle south on Route 11 in Onondaga with a large group of other motorcyclists, troopers said. …
Evidence at the scene and information from the attending physician indicate Contos would have survived if he had been wearing a Department of Transportation approved helmet, troopers said.

When foreign friends visit the States and are puzzled by some of the quirks of our Government, I often point to helmet laws — which differ state by state — as an example of how things work, or fail to work, depending on your point of view.
If the strongest argument in favor of a universal helmet law is that we all share medical and emergency costs to some degree and should therefore minimize them, what is the strongest argument against such a law?
One bizarre unintended consequence of the rollback in helmet laws: more human organs available for transplantation. From SuperFreakonomics Illustrated:

Between 1994 and 2007, six states repealed laws that required all motorcyclists to wear helmets. Here's a look at per-capita organ donations from male victims of motor-vehicle crashes in those states versus all other states.*