I actually agree with you politically on this Engineer, but I think that the left is going to need to be very careful on this issue.
I live in Cambridge, MA... pretty much as liberal a place as you can get. I was at a breakfast with other parents, there was a discussion among the Cambridge "PTA" moms about how sharing a changing room with trans-gendered women made them uncomfortable.
This surprised me. I think this is an issue where liberals can lose votes.