He did say beforehand that he'd need a second to finish the email so the flight attendant could have told him then in a polite way that there was no time. And a

He did say beforehand that he'd need a second to finish the email so the flight attendant could have told him then in a polite way that there was no time. And anyway, if they are so concerned about this, they can tell people to shut down their electrical devices 5 minutes before so that no one is late (and well anyway, there's no safety reason for this rule).