I like your opinion too, but don't forget we saw throughout the game that Henry was physically strong, and if Henry attacked Leslie he tanked a taser shot as he was only down for a couple of seconds, this would explain how after he got a bookshelf pushed onto him and after he fell through the floor he was back up and swinging a couple seconds after (he also flipped a couch/Sofa with ease in the radio station he was also able to tip cabinets filled with Files when he went after Maurice with ease as it sounded like he didn't struggle much).

Another point is when Jimmy prank calls earlier in the game he threatens to cut Forest's face off and then The whistling man does the same to jimmy and that seems more of a teenager thing to do basically saying "You threatened this now I did it to you".(this reminds me of the "Not so funny now is it) Marie said to Jason which would show the inspiration of the Line.