All loads tend to spin underneath a single rotor helicopter. They may stabilise in forward flight either naturally or artificially but after coming to the hover it will start spinning again. You then have to have lines hanging from the sides or corners so that they can be grabbed by the ground party so they can line up and hold the load in the desired direction and position whilst it is lowered to the ground.
There seems nothing wrong with that four point slinging. The combination is going to be flown very gently so any severe manoeuvres are not going to happen.
Erickson, of all people, should know that it will work.