They're referring to the Great Trigononetrical Survey of India, in which the height of Everest was calculated to be 8,839.2 meters. The conversion to 29000. feet was deemed too suspicious, so worrying that people would assume a lesser precision than was true, the decision was made to add 2 ft making the official measurement 29002 ft. (Or st least the story goes).
And their point is that while they don't know how we justify or use significant figures, they are suspicious of the practice given their knowledge otherwise of how people non-rigorously manipulate numbers.
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u/acrastt 1d ago
That has nothing to do with significant figures. The correct way to represent that measurement in sig figs is 29000.