I should also point out that when you add the Mac HD Icon to the Spotlight privacy box, the system pops up a warning dialog that Spotlight won't work on anything on the HD anymore.
A little scary but I ignored that because moments later I knew I would remove it from the privacy box.
And afterwards, I tested both search within Outlook and generalized Spotlight search. Looks okay to me.
Like Apple, Microsoft makes countless decisions about what to bother with. I guess search within Outlook didn't make the cut...