The claim that version numbers aren't the same as decimal expansions of real numbers? Yes, well, the link you just provided gives evidence for that. I'm not familiar with semantic versioning, but as far as I can tell, one element of it is version numbers being triples of natural numbers. Well then, at least in the case you're talking about, version numbers aren't the same as decimal expansions of real numbers.
In general, I would argue version numbers are sequences of natural numbers ordered lexicographically. That means they're not the same as decimal expansions of real numbers.
If you look at my comparison, you can see that it isn't a decimal number. I said (dropping the v prefix, that may bee to subtle for HN): 0.8 < 0.10 < 0.80. In decimal that would be: 0.8 < 0.1 < 0.8 - the comparison doesn't work this way (duh). But it isn't lexicographic sorting either. This sequence: 0.8, 0.80, 0.2, 0.20 has this lexicographic order: 0.2, 0.20, 0.8, 0.80, while a proper version ordering is to compare the stuff after the dot aka 2 < 8 < 20 < 80.
In general, I would argue version numbers are sequences of natural numbers ordered lexicographically. That means they're not the same as decimal expansions of real numbers.