If you want to see, you have to Look.
I know how you feel. I can't get up the nerve to ask permission, and if you do ask, the shot is no longer candid. That's one reason I rarely photograph people, especially without their knowledge.
Your a braver man than me. I half wondered whether this was a bit of an "in" joke following your meal out the other week!
I see the attraction to this type of photography - it's interesting and spontaneous and this particular one is well crafted. I do see your point, nobody wants to be labeled a "creep" or "voyeur" but maybe the results are worth a moment of embarrassment.
"Creep" depends on the motive of the photographer, and your purpose is not creepy. This is a great picture. The parallels in the picture are wonderful.