That's the thing, I can't recommend an alternative other than censorship. All I know is that violent extremist groups or identities like ISIS, white nationalism, and others can be linked in part to a good chunk of the mass shootings and other acts of mass violence that many parts of the world have experienced over the past 10-15 years.
Those are excellent points. The rise of extremism is very worrying. Have you considered the possibility that this is might not be unprecedented, and that censorship may have been tried previously?
It may be worth considering that it might be acceptable to not choose censorship as a policy. Some might opine that an inability to find an alternative should not be construed as support for censorship, and that this is merely the politicians syllogism at work.
I don't know that you can prevent hostility after combining large groups of people from different cultures. Maybe throttle the stream of immigrants from different cultures so people can assimilate?
