I guess I'm not sure what I expected. There are few other options besides putting a parachute on them and ejecting them from the aircraft. I don't know the story of who posted the image and why but there's kind of a dangerous idea that anyone can just upload an image without context and remain free of responsibility for the consequences. My first thought was that the restraint was unacceptable because it just looks awful but really I can't imagine what else they're supposed to do if someone is violent and out of control. Any other option seems liable to create more problems than it solves.
Seems like the airlines could benefit from a human-sized zip tie. Trying to wrap a moving passenger in tape seems really difficult. But I bet the adrenalin helps.