Why would I want their suit dismissed?
Suppose a Jewish Rabbi was preaching that pork is unclean, and the hog farmers complained? Would it be proper for the city or country or state to demand the Jews stop preaching what they believe?
Suppose the Hindus preached that beef is not to be eaten and the cattle ranchers complained? Would it be proper for the city or country or state to demand the Hindus stop preaching what they believe?
Note that even in your example, all the Muslims would be doing is preaching. They wouldn’t be attacking people on the streets, blowing up buildings or anything like that. Their preaching is mere words – binding only on the believers.
That’s exactly what the First Amendment protects.