Spotlight behavior for removable drives  



Running Mojave.  I have several USB thumb drives, mounted only occasionally, which I don't want indexed by Spotlight.  So I plug in one of these drives, it mounts, and I go into SysPrefs->Spotlight->Privacy and ask the system to exclude the drive from indexing.  But as soon as I unmount the drive, the system also removes it from the Spotlight indexing exclusion list.   Is this a Bug, or is is a Feature?

I am also annoyed that I cannot remove a .Spotlight-V100 file from any of my USB drives.  From the command line:

bash:sudo rm -rf .Spotlight-V100
rm: .Spotlight-V100: Operation not permitted

Anyone know a way around this?