The un-uniform plastic cylinder married into a perfectly round stainless tube really simplifies the work needed out of the epoxy. It really can’t let go unless it loses its bond to the stainless everywhere. Even then, the stainless tube can’t spin, the pin prevents that.
If it were to lose its bond the the plastic, the irregular shape now forces it to move with it anyways! It can’t go anywhere. This could stress the remaining plastic joint, breaking it there.
I think the screw into the plastic cylinder would fail sooner. The screw would want to turn as the plastic shaft turns to unlock the trunk. Remember the plastic cylinder needs to spin to do its job. Adding a screw into its center to pin down a solid metal rod would not last.
I think this really is the best solution. I had my doubts about the need for a plastic epoxy, but seeing how well it’s grabbed on to the stainless tube, I think it’s the way to go. By covering as much of the plastic cylinder as possible, I’ve maximized the surface area of the glue.