Yeah, Julia probably has a similar number of users as Rust - they just don't inject it into every breath they exhale like Rust users do.
And if you compare the IEEE to the TIOBE list, there appears to be a high degree of correlation. I think part of the criticism against TIOBE, is when people's favorite is not doing as well as they would like or a language they don't like is doing better than they expected.
Anecdotally, I feel like I see article "on" julia at least as often as rust on HN. I totally expected it to come "second" on most categories, and was very surprised not to see it there.
Then I realised that most julia articles would rarely introduce the julia component as "in Julia"; certaintly not in the same way that people tinkering with rust would be keen to report it as such. If anything I have noticed that most articles on Julia tend to be a bit backdoorish (i.e. the title is on, say, differentiation, but then you go to the article and it's basically an article about julia).
So I think it's just a side-effect of the methodology used to rank languages; not sure if it reflects actual market-share or the result of a vocal community engaging HN specifically, but julia definitely has a much stronger presence on HN than implied by this tool/article.