That's what I figured he was referring to, but you (and he, if that's what he meant) are just wrong. Your source points out that the amount consumed is taken into account:
Where does it say that the amount consumed is taken into account? That guideline is referring to the number of consumption occurrences per-week, not the amount used.
Which is the tobacco equivalent of classifying someone as a heavy drinker because they're using red wine as a trace ingredient in cooking several times a week, and considering that the same as consuming 4 vodka bottles over a span of 4 evenings every week.
Or, to bring this back to the example that started this thread, and which you seem to be thoroughly missing, to regulate numbers of radiation exposures per week. Without taking into account whether that's from standing outside in the sun for 10 minutes, eating a banana, or standing next to an unshielded nuclear reactor.
It's not some pedantic theoretical concern. There's an astronomical difference in the health risks between smoking a pack of cigarettes 4 times a week, using E-cigarettes 4 times a week, or applying a nicotine patch 4 times a week.
https://www.kff.org/faqs/faqs-health-insurance-marketplace-a...
Now, it is binary. But US federal law puts "an afterdinner cigarette once every four months" very much in the "nonsmoker" category.