I never had any OS X 10.9 Resume Download icon in my dock.
I followed all the various fixes, and never noticed it appear. It certainly never wanted to d/load from the App Store window.
So I gave up and used another machine to d/load it.
While it was d/loading I continued my work on the main Mac.
I have my dock set to auto hide, so only see it when I need it.
Next time I went to the dock... There was a Resume D/load Icon.
So maybe after deleting the various files/ folders associated with App Store, as detailed previously, do a couple of shut downs/ restarts, maybe re opening the App Store in between,
Too many dock items? I don't know, but is there a limit to the number of items in the dock? I know I also removed some dock icons around this time. Maybe removing some made room for the Resume D/load one I did not see?
Shooting in the dark with that but anything worth a shot