As far as the OP goes- I would have been sooo angry!! I hope you told your dd, very loudly, that it wasn't her fault, but rather the fault of the very nasty mean lady, who will no doubt get her comeuppance when she has to get down and scrub the floor. I too would complain.
I work in a small surgery and we often have kids who need the toilet, and we always let them go- why wouldn't we? Even though it is a tiny staff toilet and all our handbags and jackets are in there (as well as our X-ray developer!), and so is probably against every health and safety rule, who wants to see a kid distressed? An old man used it once and pooed on the floor, which was just gross, but heyho- better in there than in the waiting room!
Bit confused re Flashman and the x-chromosome- I thought you were a guy?