If you select uncertain and enter a middle name or initial, "uncertain" will display on the private view, just as it does with the other data fields.
If you select uncertain or certain, but do not enter a middle name/initial, "middle name?" will display.
If you select certain and enter a middle name/initial, the name display will be clean.
If you select no middle name, but enter a name/initial, the name/initial will display - and you will get a suggestion to fix it!
At least, these were the results of my recent tests.
edit: forgot to mention that I am a certified mad scientist, so you can trust my results!!