Well, it depends. If you believe that Armin Meiwes https://en.wikipedia.org/wiki/Armin_Meiwes https://en.wikipedia.org/wiki/Armin_Meiwes is wrongly imprisoned a

Well, it depends. If you believe that Armin Meiwes https://en.wikipedia.org/wiki/Armin_Meiwes https://en.wikipedia.org/wiki/Armin_Meiwes is wrongly imprisoned and must be released, then sure; you also win the who's-the-most-consistent-libertarian contest. On the other hand, if you believe that humans possess certain unalienable (which means not revokable, and not relinquishable, even voluntarily) rights, then the fact that the football players are volunteering for brain damage is not necessarily enough to make it okay.