He beat a dude in the street of a foreign nation... why shouldn't they hold him? Would you think it was ok if Swedes came here and started beating random people in the street and just got to go home?
I think this is a matter that is not being judged fairly. Yes, it is a foreign nation but that doesnt give the citizens the right to harass foreigners or stalk them. Rocky acted in self defense after various verbal warnings to his assailants which i believe were under influence. If he had no respect for the law,he would never had honored the invitation of the authorities. It is inhumane to keep him held up in a poor facility without presenting all the facts quickly.
If that is the case, the legal course of action would be to call the police. I get in the real world shit like this happens, but it also doesn't excuse it. You don't have a right to beat the shit out of people just because they are drunk and following you. That is not self defense.