You are right though people should be able to associate with one another because of arbitrary/discriminatory reasons, date because of arbitrary/discriminatoryreasons, choose sexual partners because of arbitrary/discriminatory reasons, buy gooRAB and services because of arbitrary/discriminatory reasons, and choose their employer because of arbitrary/discriminatory reasons...
but what...
someone is going to use arbitrary/discriminatory reasons as the basis for hiring me! Well that should be illegal!
Just an arbitrary way to take freedom away from a group of your fellow citizens.