The thing that annoys me is this isn't any way a legit concern by the right. 5 years ago none of them probably knew what a trans person is, let's call it what it is, the reactionary right finding a new group to pick on because they lost the gay marriage fight.
This is the left moving onto something more out there (in their spare time, when they aren't busy going after Christian businesses for not taking part in gay "weddings") because they won- at least temporarily- the gay marriage fight, so they need something new. If they win this, they will find something more bizarre in 5-10 years that would have seemed unfathomable to us today (I could see, for example, a push from the left to create animal rights and ban people from eating meat).
The slippery slope is pretty idiotic on this. Your side warned us that gay marriage would lead to people wanting to marry their dogs and would open the door to polygamy etc., none of which has happened. Massachusetts has has marriage equality for going on 13 years now and tons of people aren't coming out of the woodwork up there to want to marry their pets or plants or vacuum cleaners or whatever else.
I see this attack on transgendereds as the right's new piņata now that they've lost on marriage equality. Republicans who condone this but stay quiet on Trump's Russia situation really have no conscience. "Hey angry working class whites! Vladimir Putin isn't your problem; your problem is all these he-shes trying to molest children in the bathrooms!" I'm sure that's exactly what Jesus would think too.