Descrimination

I was recently applying to be part of a focus group. When I was given the screener, they asked whether or not I ever had any interest in joining the armed forces (they were looking for people who were interested in the armed forces). I told them yes, but I would not be allowed to join the navy because I have schizoaffective disorder. They told me that they were unsure whether or not I could be part of the focus group and that they would get back to me. They never did.

Is this discrimination? Should I be talking to a lawyer? I don't think they're allowed to stop screening me because of a mental disability?