But allowing a woman in the same situation is OK? Not campaigning to stop women being scout leaders then? There are plenty of ways to ensure privacy in scout camps, and I'm pretty sure communal showers went out of scouting a long time ago.
Arguing from 'common sense' means arguing 'without feeling you have to justify any bigotry'.
You've never heard of unisex restrooms in corporate buildings? They're quite common now.
One at a time and there are locks on the doors.