BTW haven’t many of us often used public loos where cleaning was in progress. They often have a sign saying Caution, wet floor, or to warn you that there may be - shock horror! - a male cleaner.
So I really don’t see B&Q’s issue.
Worst I’ve known, though, was when meeting a couple of friends at a garden centre where we were going to use the cafe - only to find that the water was off in the whole area, so not only cafe and loos closed, but no use going to nearby pub, either - one friend was already desperate for a wee and it was a good half hour on buses to anyone’s house.
She did make it, just!