TC - was this fed back to the flight deck crew?
Back to the 'mesh' incident - we are pretty close to another Helios here with these 'slack' SOPs -
yes, c/c mask up (and ENSURE any pax do too).
After a SUITABLE time, attempt contact with F/deck - PDQ in fact if no announcement or emergency descent is detected.
Sauntering forward [presumably without a bottle (of oxygen)] is just plain stupid and a bottom needs to be kicked.