The stupidest of the stupid are the ones who claim that you can, in your heavy helicopter, make a fast approach, do a big flare at the bottom, then fall through and hit the ground hard and then call it SWP. Oh. My. God. But yet there they are.
No-one has called that SWP so I'm not sure what your point is.
I agree that CH46 isn't SWP, it is just a punchy arrival gone wrong when the wheel gets caught - sadly people died in that one.
(There are even those who claim that the advancing blade of a rotor in forward flight flaps *up*! Amazing. But that's a different subject.) Everybody is an expert on the internet!
it tries to but is prevented by the pilot input on the cyclic or the autopilot moving the actuators. Take a helicopter, trimmed to a 90 kt cruise - then add another 30 kts of wind without doing anything else to the controls - what happens???? Flapback, so which way is the advancing blade flapping????? Then you push the cyclic forward to compensate and that makes the blade flap down instead.