'switching' a compressor on and off like mad max style would burn a magnetic clutch out in about ... oh, i dunno ... 5 seconds! seriously though, it can me done, but not magnetically like an A/C compressor.

the SC12/14 chargers use this magnetic clutch to disengage the s/c at idle via a small throttle position switch - it also comes on as soon as the throttle is touched and the switch deactivated, so it's not having to speed up the rotors at 4000rpm or whatever you decide to switch it on at.

i've seen people try to switch these cahragers on, only to be left with a funny smeel and a dead s/c clutch when they pop the bonnet.