As usual, very good dance rules, that were said to newer dancers in an atttempt to curb bad habits, seem to morph into dogma that allows no rational thoutht.
I would tell any man who was pushing with his left hand, and using it as his primary lead, that he should concentrate on leading with his body.
I would also argue that the left hand should be part of the mans frame, and therefor it would always be a part of his lead.
I know that some dancers have pretty much abandoned the use of the left hand, my belief is that the breaking of the frame, so you can say you are not using it for leading, is foolhardy.
In my opinion, the left hand is part of a man's frame.
So I guess we must agree to differ.