All of your suggestions are way worse for the feeling to play Hammond.
I think the boop nerf is by far the best they could do to actually nerf him while still keeping his playstyle intact.
It is by no means minor, there is no point in a nerf if it is so minor you do not even notice a difference but it keeps the hero intact, what a damage nerf, or a piledriver nerf as suggested by you would not.