100% agree, Detector -- We have the very same brand of saw -- it's a Skil reciprocating saw -- electric. It's not super-heavy, but it does have some weight.
It would be very, very difficult to keep the saw where you wanted it to go when cutting through a femur, especially. First you have to get through the skin & fat, then the muscle. There is a lot of mass in your upper thigh. Think about it. You really could do a much better and quicker job of it if someone held the leg still (sorry about these words) so that one could hold it in place. Same for the rest of the body. And body matter spray? All over the place.
No way GH would let AH sit around while he sweated through the dismemberment. He's too worthless to do anything by himself. Plus he knew she wanted poor LA gone -- prolly more than he did -- "Get over here and help me." (I can just hear him...)