I was under the impression flight crews had a set or two of handcuffs onboard. The memo seems to indicate something for this purpose is.

> Instead, he is asking crews to use the items aboard flights designed to keep flyers at their seats – and prevent them from becoming a hazard to the flight or other passengers.

I'd also note the Frontier incident that made the news was passengers duct taping the miscreant, not the crew. If I were a flight attendant in this situation, I might pull the "oh, whoops, dropped a roll of duct tape... would one of you grab that for me?" tactic.