Well, yeah, one could do anything, it's just a matter what's a realistic amount of work for such a minor feature...
Based on the code in your other PR, the checks and conversion for relative/absolute paths are just a dozen or so lines, most of it declarations and cleanup. Then maybe another dozen or so lines of GUI code.
I don't have time (and motivation) to write this and I guess nobody has time to review such a patch...
It looks like you've working on variations of this for 7-8 years.
But I still think moving the project file while the project this file describes is loaded would be really tricky.
Update the paths and save/close the project. Move and reload the file.