You must also compare with `ls foo-<tmpname>` which is really another level of complexity. Next usage is far more efficient

> ls foo.pdf*

>rm foo.pdf+TAB completion+arrow down?+enter

However, if things are correctly implemented, you’d never even need to worry about \jobname.pdf(busy) at all, should it be from the CLI or from the desktop. The only purpose of \jobname.pdf(busy) is eventually to be deciphered, and this is far easier for most people, who only know ‘_’ for math subscript (I had already tested on my students for "synctex(busy)").

Only tools that clean things up (« Remove aux files » ) could eventually manage a new file extension but that is not a requirement.