Generally yes, but once certain people get violent or disobey specific rules, it is the job of the government to stop that. Otherwise things escalate badly.
Infiltration also isn't as easy as it sounds. They can use that as a defense. Which actually happend several years ago. They failed to get rid of the NPD, a Neo-Nazi party, because they couldn't be sure if their plans were legit.
https://en.wikipedia.org/wiki/National_Democratic_Party_of_G...
Getting a company to obey the law is probably easier.