This is a difficult one. As someone who lives in HK and flies CX, yes, these passengers do exist. But in Asia the whole US approach ("pull out a gun / drag people off the plane / ban people from flying) kind of thing does not have much traction. On balance, I'm happy about that. It seems like living hell flying in the US with all those crazy rules and too many FA and security staff deciding that they can cause passengers hell whenever they like. In this case, I side with the ISM, but wouldn't want police responses to become the norm.
I had a similar but opposite experience on a Sri Lankan flight out of BKK last year. Flying (paid) business class. On board, plenty of open seats and I noticed that my assigned seat had no space under the footrest so nowhere to put my small bag. Asked to move. Was moved. All sorted... or so I thought. Then the ISM (a man) comes along and ask's what's wrong. I point out that the seat didn't have any room under the footrest, this one does, all good. He then tells me I'm wrong. That all the seats are identical. So I say something like "well, if you look over here....." (just trying to point it out) At which point the guy becomes really abusive and says I'm causing trouble and he's going to throw me off the plane. Seriously crazy. The ground staff came on board and (from what I could see) mostly tried to calm the bloke down. The other FA's (all ladies) looked sympathetic and were really nice to me the whole flight. Eventually we pushed back and took off. I have no idea what was wrong with the bloke, but I suspect it was being "questioned" by a woman. This is the risk we face if we make the ISM all-powerful. The lady in the OP clearly was fine and doing her best (and I have never comes across anything on Cathay even remotely like this experience on Sri Lankan). But not all airlines staff are equally well trained (or balanced, it would seem).