If it says waiting for deployment, then you're already getting dragged into the War Barge/Match, It takes a while for the info to transmit though, so if it already started, then it's too late.

one can still cancel when "waiting for deployment". So the SL cancelling should cancel for the whole squad. That's all.

The squad leader gets a longer "warning", everyone else doesn't get the "waiting for deployment" until it's too late though. I literally get the message, and then I'm in the match a second later. It can't be cancelled at that point because the system has to check, but it doesn't have enough time to make the necessary changes. it's like trying to restock while it's about to load, it won't work because your to far in.

The SL gets the message the instant the game finds a possible match, everyone else gets it the once it is already trying to put you in that match. It can't be cancelled because at that point it's no longer checking what the SL wants, it's focusing on getting you in the match.

Yeah well, during the time when the SL is the only one having the warning, cancelling wont stop the other members from the squad to be dropped into that game.