Use of mother tongue should only be an issue in public office or when addressing the general public where non speakers of the language are present and have a reasonable and legitimate expectation to be addressed in a language they understand.
If I start a church and designate it as a Kamba language church, - a Luo, Kalenjin, Pokomo etc would be misguided to pop in!
Again I don't see any problem in people choosing to keep their culture alive in distant lands.
Isuni yilu yi maa me muyo - ni Mbisuu