I feel like you are missing the rather obvious or else the note implies. Luckily the law is not so rigid as to be hamstrung by such sophistry. I didn't assault you, I merely invited your face to make an acquaintance with my fist!

The reason the note works is banks don't want to pay the cost of having their employees getting their brains blown out. Passing a note with this understanding means one knows they are making a threat.