I seem to recall that airlines recommend you keep your seatbelt fastened as much as possible, regardless? - in case of CAT - which often strikes without any warning?
There have been many instances of passengers wearing seatbelts, who were uninjured after a severe CAT event was encountered - whilst the injured ones were the ones roaming around, or who had their belts unfastened.
As for passengers intruding into the galley, I would regard that as being just plain "pushy". I would never dream of doing that as a passenger. It's the equivalent of walking into a restaurant kitchen and demanding items.