Looks like this code broadcasts old, unedited version of the post if the length of Buffer is lower than the length of patch. It should broadcast the edited version, otherwise post wouldn't be updated.
Why is the Buffer created from the original body? Shouldn't it be created from the edited body?
Working on posts editing for my app based on tutorial 12 I found a piece of code that might be incorrect.
https://github.com/steemit/devportal-tutorials-js/blob/master/tutorials/12_edit_content_patching/public/app.js#L69