I think we should leave the Companion restrooms to people with mobility issues and people who require assistance in the bathroom (which category may
possibly include single parents and their opposite sex children, but not always).
I have no issues with Dads bringing their daughters into the men's room. I mean, really, it's not like walking into an orgy! It's just men trying to pee. Even if the wee lassie spots a man standing at the urinal, it's not as if she'll be scarred for life, blinded, traumatized, any other such nonsense.
I also have no issues with Mums bringing their sons into the ladies' room.
And I seriously don't care what's in your pants. If you present as male and would feel more comfortable using the men's room... then use the men's room. If you present as female, use the ladies' room! It's all the same to me.
And when children start expressing discomfort at going into the bathroom with their opposite gender parent... then they shouldn't have to any more. Respect the child's preference. Respect the adult's preference. Just, respect people.