You keep hammering on this claim, except it's clear Janus doesn't believe that he's benefiting from it. It's actually quite easy to find examples - from the very beginning of the labor movement up through today - of labor unions screwing over certain classes of members for political reasons. So it's pretty easy to imagine how Janus would have reason to believe he's being forced to pay for something that has a net negative impact on him.
He’s already entitled to a refund of the portion of union dues (if he decided to join it) that go to political activities. This is the Beck decision in the late 80s.
Actually, it is the role of the judiciary to determine if the legislature has overstepped the bounds of the authority granted to it by Congress, by providing public labor unions with a degree of special authority granted to no other entity. And, as explained elsewhere in this thread by an actual lawyer, there's a pretty solid case that it has.
Again, if this is what he believed, then he would be suing to get out of the bargaining unit.
The entire suit is a scam to weaken the power of unions. If the union has to act on behalf of you, but you don't have to pay, then very, very few people are going to actually pay for the union, and it will die.
The courts have already ruled that the unions can create contracts that exclude non-members from bargaining units (and therefore refuse representation to non-members) as long as they don't charge the non-members agency fees. If Janus wins the right not to pay an agency fee, that's what they'll do.
The only scam is in pretending that the unions are forced to represent people like Janus whether or not they receive fees. That's nonsense; it's their decision entirely to include non-members in the bargaining unit.