If you insist they give up their culture immediately you will be seen as trying to take away their culture. Just like how gun rights advocates perceive attacks on gun culture.
Solidarity is a normal reaction to real or perceived hostility. In history the social pressure to assimilate resulted in immigrant collectivism in order to support each other; Chinatowns, little Italy and a myriad other ethnic enclaves formed partly because of this pressure.
You are assuming I live in an area without Muslim immigrants.
My experience has been the opposite. Generalizations and stereotypes are harmful.
I have seen immigrant Muslim comedians, cashiers, restaurantiers and entrepreneurs. I have seen Muslim women in western dress and makeup. I have seen immigrant Muslim children with all the toys and brands that other kids have.
Our anecdotes support my point: if the host culture is hostile people cling more tightly to their ways, the familiar that provides security and comfort.
Yes that is my original point: if you accept and help immigrants they assimilate faster. Pressuring them to abandon their familiar culture for an alien one hinders assimilation (in response they seek support from more friendly people: other immigrants).