I went to buy a meal at KFC Braamfontein. I then asked to use the restroom that was locked, to

I went to buy a meal at KFC Braamfontein. I then asked to use the restroom that was locked, to my surprise A lady working at KFC Braamfontein refused to open restroom (toilet) for a reason that She just cleaned and that the floor is still wet. Which interprets to me that customers at KFC makes their toilets dirty.

Is this reasonable?