Both absence of seats photos and very small probability about some messing with the loo is because plane was still climbing at the point of event, so pax was seated and fastened and any loo excursions was prohibited.
Really. You think because the aircraft was still climbing the belt sign must have been on, therefore all pax were seated?
Amazing.
Are you a pilot? Do you fly as a passenger very much?
The belt sign in
many airlines comes off after transition (FL100-FL150) if in smooth air and nothing visible ahead that poses a turbulence threat.
NB for the pilots, yes I know about transition down as low as A030. Trying to KISS