Heard that too.......just checked with a captain (BA) pal and he confirmed. Crew have to confirm ‘cabin ready’ to the flight deck, which they won’t do unless everyone is seated and belted, no exceptions. No ‘cabin ready’ signal and landing would be aborted as cabin considered not secure.
Edit -...
Indeed. Plane I was on recently was hit by lightning about an hour from KL. Bloody massive bang and flash of light went right through the cabin. I nearly dropped my red wine.
Have experienced severe turbulence a few times, it’s scary as hell at first. No way the crew will (or should) let you...