Paula, those supposed "big protective husbands" wouldn't care about laws or lack of laws. If your scenario were realistic you'd already hear of TG people encountering these situations regularly. They aren't. You're just spreading groundless fear.
Consider the number of GGs who have masculine features. Do they get challenged? Of course not, because challenging them would be be embarrassing for an individual and lawsuit-inviting for a business.
I'm 6'2". I stand out. People remember me months after a single encounter. I have some hard-to-hide male features. I use restrooms in a wide variety of situations. I stand in line when I have to, chatting with the other women because they want to chat. How they perceive me I cannot say, but I have never had anyone question my presence in the least, either directly or via a "big protective husband."
Now, I'm just one person, but it's logical that if there were a serious problem I'd have encountered it at least once in five years of being out and about.