It doesn’t really reduce risk much because you’re literally about to take it off anyway in that same space.
If I’m in transit on airplanes and in airports for 8 hours and I wear a mask for 7 of those hours, the one hour (or probably less) that I take off my mask to eat a meal doesn’t completely negate the good that wearing a mask does for the rest of the time. I’m still reducing my risk (or the risk I pose to others around me) for 88% of my travel time.
There’s a huge difference between sitting at a table by yourself (or even with a family member) and, say, sitting next to a stranger in an airplane. Walking through the restaurant and keeping the mask on so as not to catch or give anything in passing is sensible. Greater distance means lower risk.
I’m going to take a wild guess that the infectious disease doctor knows better, but by all means please proceed, Mr. Dunning-Kruger.
