This is already covered by laws prohibiting incitement of violence. Muslim Advocates, like any other aggrieved party, can collect evidence and submit a complaint to local authorities.
As far as the Muslim specific example, I think they should police their own backyard and submit their complaint for broader consideration once they can establish that the internet is no longer used for jihadist purposes.
As far as the Muslim specific example, I think they should police their own backyard and submit their complaint for broader consideration once they can establish that the internet is no longer used for jihadist purposes.