There is video of the security assaulting him and some others, including the person taking the video. Even if he is an outright nazi (debatable, but he sure us

There is video of the security assaulting him and some others, including the person taking the video. Even if he is an outright nazi (debatable, but he sure uses nazi stuff for "trolling" and "humor" as he puts it), and even if he refused to leave (he said he was in the process of leaving, CCC said he refused to leave) etc, this is not OK nor is it legal. You call the police and, file trespassing charges and have the police remove him and the courts sanction him. Even if he was physically violent in the time prior to the video (which nobody alleges, just a hypothetical), he clearly wasn't anymore at this point, and you do not get to retaliate; you file assault charges and have the police remove him or arrest him. If he screamed nazi salutes or demanded the murder of ethnic groups (which nobody alleges either), then... you call the police for trespassing, and since this was in Germany, for using prohibited nazi signs/slogans (§ 86a StGB) and or "incitement of the public" (Volksverhetzung, § 130). If he was filming (he said he did start to film once security became aggressive, CCC said filming in the space is a big no-no in general), then you still do not get to assault him. The only legitimate reason for security to use violence would be if they had to defend themselves or others from physical attack. And no, words and disobedience are not the kind of violence that entitles you to violent self-defense.