I’m not really clear on why the turbolift would fall in the first place… Is that a gravity plating thing? I guess gravity plating must work without power?
Also Picard knew it was going to fall… are we to infer he’d rather be pancaked than spend another moment with those kids?
The way gravity plating works is not given as far as I know, Perhaps the gravity generators simply alter the number of gravitons in an area of plating. Once that value is set it remains until changed again. A sudden power spike can cause the generators to withdraw the extra gravitons, as a result sometimes certain kinds of emergency can “turn off” gravity in an area of the ship.