In this RT clip, the case is explained well, but includes one critical error:
Notice at 0:42 in the video there are a series of tweets.
Here is the actual translation:
#Muslima: school excursion: forbidden! Swimming classes: forbidden! #Mosquevisit: compulsory for German children #No
So in fact, Muslims in Germany DO NOT have to go to field trips, swimming classes or sex ed.
But the German kids MUST go to mosque by law.
A small error but a highly significant one.
Even if RT's translation was correct however, the logic does not follow. Because, for example, Japanese immigrants to France may have to take French, French history and how to cook with dairy products by law in schools. But it does not follow that French kids would have to go to a Shinto temple or learn how to speak Japanese.
The Japanese people moved to France voluntarily, like the Muslims who went to Germany.
RT appears to be relying on an overdeveloped sense of parity and faux-fairness to sell that idea.