Well he wasn't wrong. Rotorcraft operations are or will be banned in many populated areas for exactly that reason. If they have to move a high volume of air it's going to be extremely noisy no matter what tricks they play with blade shape or whatever.

He also makes the excellent points that keeping them in the air is very energy intensive and that they pose a risk to those underneath them, in case of failure or something falling off them.

I wonder if asymmetric blades like in fans could work and if they would be any good for reducing the noise.

There has been a good deal of economic incentive for finding ways to reduce the noise of the fans in turbofans for a long time. the relatively recent introduction of chevrons on the exit end of fan nacelles shows how even minor improvements are pursued. It is unlikely that an opportunity for significant improvement has been overlooked.

Also reduces thrust.