sure they are - - they have to pay a fee; others don't. It's true that the SAME RULE is applied to everybody -- ie, don't discriminate, or associate with the BSA, or you'll have to pay a fee -- but that's an unfair rule, that punishes free expression and freedom of association.
What if a rule said, DON'T engage in gay conduct, or you'll pay a fee to use the city parking lot. You could say, nobody's being treated different because the same rule applied to everybody, but in fact people are having a fee imposed on them because they're gay.