You aren't allowed to discriminate on the basis of personal preferences. The simple rule they can act on is if it was illegal, which in this case it was not.
And still you're living in La-La Land.
You seem to think that law makers can regulate people's internal thought processes and judgments. As a manager of people, who hired and fired, I was once advised "discriminate all you want, just do it all in your head". As you form opinions of current and potential employees you ALWAYS filter it through your personal beliefs, preferences and values. If you don't verbalise any of those, however, and you avoid blatant discrimination, no one will be able to prove it. That's life.
Actions, legal or otherwise, have consequences. Johns CANNOT do his job as a media personality if the viewing public no longer want to watch him or listen to him.
On this basis, the one job he definitely shouldn't lose is the coaching gig (unless someone can successfully make a case that all this means he lack the leadership credentials required ... but I don't personally believe that).
I agree that there has been a degree of scapegoating and I think natural justice is perverted by the whole issue resurfacing seven years after the fact (with little or no new information). That doesn't mean Johns is completely faultless and undeserving of these consequences.
Ultimately, I think it's mostly a media beat up and there are agendas galore at play ... but these guys need to sleep in the beds they make for themselves - something I think Johns is actually doing an admire job of accepting. He's certainly saying and doing the right things, in my opinion.
He'll bounce back and I won't have any problem with that.
I just don't think "we have a right to our sex romps" is a defensible position for any footy player. If such romps are truly above board and done with a smidge of common sense then we wouldn't even know about them ... the fact that one party ends up making a complaint is what takes them from the realm of private to public.
Participants who do not conduct themselves with some common sense and decency, however, will be judged by their "customers" and if the fans and sponsors find such behaviour to be unpalatable, they might lose their livelihood. That's life too.