The real issue that you solved with the Teflon tape on the pipe threads was the O ring between the top of the pipe where it contacts the Jack nut.
The piston shaft keeps the O ring in place between the pipe and jack nut, and removing that shaft allows the seal to fall inward (assuming you even reinstalled the O ring as one of the two jacks I purchased for this project did not even have one).

In the original write up I don't even remember him even mentioning the part of the project where the pressure needs to be contained between the internal pipe and top jack nut.

I just cut a 1 inch piece of the hollow piston shaft and just JB welded that piece into the main pipe with a bit of it sticking out just high enough to help retain the O ring when JB welding the pin hole.

I'm willing to bet that one guy that had it fail so soon had the O ring slip out, (or inward) and stopped sealing the gap.

Other than that important issue, nice write up.

My first one will be all Purple with Yellow barrel/pump and all Red with a Yellow barrel and top nut (the only colors of powdercoat I had left).

I will also be adding the Teflon tape to tighten things up and as added pressure security.