even in the article they try to slant it like "poor karen!" and it's annoying.
Even if you were to assume that she was having some sort of mental break down or something- which is entirely possible- You still have to maintain the physical safety of yourself and the other passengers on the plane first and foremost. though I'm a little surprised they don't have zip ties or handcuffs on board for unruly passengers... or, uh.. .something more than duct tape...
I think they had zip cuffs, they just used the duct tape to keep her in the seat and keep her from spitting. They made the right call, and that lady definitely needs some kind of mental health intervention.
I disagree on the duct tape of the mouth. There needs to be a better way to handle that than making it harder for someone to breath. Where they keep the zip cuffs, they should probably have a spit mask or something.