The passenger allegedly told a flight attendant about “wanting and needing to exit the aircraft now” then jumped on her, injuring her neck and wrist, authorities said in a report.
Summary
Passengers on an American Airlines flight from Milwaukee to Dallas-Fort Worth restrained a Canadian man with duct tape after he allegedly attempted to open a cabin door mid-flight, claiming he was the “captain” and needed to exit.
The man became aggressive, injuring a flight attendant as he rushed toward the door.
Several passengers, including Doug McCright and Charlie Boris, subdued him, using duct tape to secure his hands and ankles.
Authorities detained the man upon landing, and the incident remains under investigation.
Well, not from the door opening, you are right (pressure difference and such).
But he already injured a flight attendant, so I guess he wasn't going to say "oh well it doesn't open, I tried, I'll sit down quietly now".
That depends on where in the flight he tried to open the door. The article says mid flight but that could mean anything.
Above 10,000 ft he wouldn't be able to open the door because of the pressure difference but below that and he would have no problems since the cabin isn't pressurized and the doors aren't locked with any key or anything.