It is not about whether you know that the other pilot is playing with the stick it is about knowing which corner he has parked it in.
No it isn't. If the other pilot is flying the aeroplane and the right performance is not being achieved you take over and fix it. I don't give a **** where the other stick is. If I want to control the aeroplane I push and hold the take over button and fly the aeroplane. If I know the correct Power and Attitude to set the performance will follow. If I don't know how to fly the aeroplane I should be there.
In the Air Asia crash the red button was pressed twice but for only short periods .... so it was effectively useless in this scenario with these two pilots. They didn't know how to fly the aeroplane.
It was also useless in AF447 as it was not used at all. They didn't know how to fly the aeroplane.
Have there been any examples from the cruise where it has been used successfully? I rest my case. In the cruise, not that I know of, but there was a case where a side stick had been miss-wired by maint, not checked properly prior to flight and just after lift off the Capt (PF) put in a roll command and the aeroplane rolled the wrong way. Cant didn't know what was happening. The FO took over, with the Take Over Button, used correctly to lock out defective side stick. They safely returned and had the side stick replaced.
Another thought. In a conventional aircraft I might be making the wrong control inputs, you might see this and try to take control. I am physically stronger and I win the fight over the controls, so we crash. Or, with a side stick, you don't like what I am doing, so you (knowing how the flight control system works because you are not an idiot, have thought about these things and have been properly trained) push and hold a button with your thumb and now have complete control of the flight controls.
These crashes aren't the fault of the aeroplanes. They are the fault of the 'pilots' who don't know how to fly the aeroplanes they are in charge off. These guys are the products of the aviation systems modern aviation now follows. CX is heading in the same direction. Unless wee change our ways we will crash an aeroplane, killing hundreds of people. The DFO has been warned.