I don't see a problem. To me it is similar to the situation where a business is allowed to refuse service to anyone at their own discretion. This has been used to discriminate openly but is still legal. The customers they were refusing to serve were also paying customers.
There has to be a point beyond which some things are simply not allowable. In the past, societies have grown and prospered by codifying sets of standards by which others judge your behavior and then to define and apply sanctions to those who refuse to play by the rules laid down by society. This is how laws came to be passed that allow or restrict behavior widely seen by society as criminal, undesirable, dishonest, etc.
We (any group of citizens or people with a common interest) need to be able to agree upon whether something should be allowed and once that determination is made, codify the law and define appropriate sanctions or punishments for those who choose to color outside the lines.
It is generally accepted that promoting violence, advocating for murder of others because they exercise their right to vote for a different party, providing support to those whose goal is to sow dissent and to divide the citizenry using lies and propaganda, supporting Nazis or other reprehensible characters, etc is simply not copacetic and those who choose that path should face sanctions.
The very least that you should do is to silence the messenger whose goal is to destroy you, your relationships, your society. Use their own message against them to educate everyone about why the things they are promoting are wrong and unacceptable.
Rock and Roll Amazon!