Actually, even with zero thickness the pinhole appears elliptical from an off axis view; the finite thickness only increases the problem. In truth, I'm in basic agreement with the idea that it's not necessary to calculate the stuff to death, just put something together and take some pictures. I view it a bit like cooking/baking without a recipe, sometimes it's fun to blur some boundaries!
Yes, of course you're right; I poorly worded my response (or is that "worded poorly"...).
In case anyone's curious, here's the thread over on F295 that talks about "exposure mapping", which morphs into a discussion about real-world pinhole "tunnels" vs 2-D imaginary pinholes, and the difference it contributes to off-axis exposure.