Travel with C Permit [former asylum seeker]

Hi EF members,
I have a question if any one can provide me more info .
I have a friend from Turkey , he is in Swiss from 2006-2007 and now he has a C permit , but I asked him if he can come with me to visit Turkey but he told me that I came in Swiss als Asylum Seeker and he can't go there any more until he receive a Swiss Passport, can anyone tell me how is this , or he really dosen't have right to go , or he doesn't know anything.
First he had N Permit , then B , then after 5 yers received C Permit. He is working 100 %.
Any explanation is appreciated.

Thanks,
M