I'm not sure how to answer rather than to say "it doesn't", that's not how we parse the word stops. However, that's ok, because Title: isn't what you're supposed to use, it's title:, so this behavior is by-design. All ninja search options should be lower-case as the search help page shows, those are specifically what we're looking for.

I added a few cases in the new search parser to handle this, advanced options are all now case-insensitive (rather than the native lucene field handling that was used before).