No it's definitely a flaw. The analysis doesn't model what he thinks it models. He claims that it doesn't matter by (correctly) pointing out that adding a diagonal doesn't change anything, and that hides the modelling assumption he makes:
That there is the same absolute number of people choosing to stay within every language studied.
His analysis would only be correct if the number of people who choose to stay with Java at any moment is equal to the number of people who choose to stay with Rust. That is absurd and hence the eigenvector is meaningless.
Doesn't exactly matter much given that this is just a bit of fun on a blog post though. :P
Doesn't it make sense if you ask: Given that someone will change the language they're using (and writes a public blog post about it), which are they most likely to change to?
It's not unreasonable to use that as a proxy for industry trends. I recall reading about manufacturing jobs which, sure, might have lots of factories not changing, but the ones that do change _definitely_ opt for more automation with fewer workers. That's still a trend worth thinking about.
