Mojave Finder Misbehavior

I have two unibody MBPs, a 2012 15" and an early 2011 17" (w/bad GPU permanently bypassed), both running 10.14.6. Set ups on both machines are very similar. I'm a Path Finder user, and am used to keeping Finder closed, except when needed for specific tasks (e.g. installing an app to avoid quarantining). On the 2012 MBP this works seamlessly.

Problem: But on the 2011 17", Finder will launch itself under the following specific circumstance: In any app, when I "Open" the Open File dialogue box, Finder launches. This does not seem to happen when the "Save" dialogue box comes up, only the "Open" window. Even more specifically, Finder only launches upon the first highlighting of a file or folder in the Open dialogue; i.e. just bringing up the Open dialogue doesn't launch Finder, but as soon as any item is selected (without yet clicking Cancel or Open), Finder immediately launches.

As I said, this doesn't happen in Mojave on the 2012 MBP.

I know that one answer to this problem is for me to stop being so obsessive, and let Finder stay open. (And I have zero negative side-effects of keeping it closed.) I'm hoping someone has at least one additional answer.

(If it's relevant: Both machines are maxed out on RAM. I use two SSDs per machine, one for the OS and one for data.)