Fights and Duels - Legalize them please!

Today I found outrage again on some Polish forums. This time it was due to the opinions of a certain candidate for the Polish Sejm from the political party I support. This relatively young candidate, whose chances of being elected are below absolute zero, has been endorsed by some football fan associations because he is one of the hardcore fans and supports certain practices which are part of what is considered in the mainstream as "hooligan behaviour". Namely, he has spoken in support of legalization of ustawki. These are pre-arranged meetings of groups of fans who then beat the living daylights out of each other in some remote location (the location has to be remote so that they don't attract police attention). This kind of thing is still popular in Poland and many Eastern and Central or Southern European countries. An example can be seen here. As we see they are teams of equal numbers with captains, coaches, and tactics. It is all pre-arranged and the rules are agreed to beforehand.
So, why shouldn't this kind of thing be legal, even if society at large finds it outrageous? It's completely voluntary for all participants, and the doctrine I subscribe to Voluntaryism, would seem to not be violated. When I started arguing with some people that this is in no way different from boxing (an accepted and widely popular sport in Poland) people started calling me names (this I am already used to) and using stupid arguments. One of the most common arguments used was that boxers have 'medical help' available to them, and the hooligans do not. They could get hurt! First of all, this seems strangely hypocritical, since most of these commentators say they would want the "primitive hooligans" dead anyway. Secondly, this is completely illogical. Medical help does not make something moral. In war, soldiers on both sides have medics, but most wars are immoral because they consist of aggressors and defenders. Introducing medics onto the battlefield does not make the battle moral!
Another argument used is that boxing or MMA fights are essentially controlled by regulations and external third parties (such as referees) who can stop the fight at any time. But this is a doubly-wrong argument. First of all, the regulations and third parties (such as referees) only exist there because the two fighters agreed to it in the first place. If they agreed to not having refs, there would be no refs! Nobody is allowed to force third parties into a voluntary agreement (this is the second rebuttal). For example, if I find you in bed with your wife, I cannot arrest you on the charges that your common marital bed does not meet my specifications for a husband-and-wife couple. That would be ridiculous.
Equally as ridiculous as stopping behaviours such as ustawki or one-on-one duels. Even anti-liberal Alexander Hamilton would agree with me.