I think the thought there is just that STEM nerds tend to have stable high-paid jobs and thus good credit, and so OSes/browsers that nobody but nerds use / would tolerate using, are signals of having good credit.
Income, or even 6mo income history, doesn't predict how likely you'll be to get another job if you lose your job. What lenders really want to know is how in-demand you are in the market, and so what they should predict as the "floor" on your future income.
Add to that how likely someone with your personality-type is to just decide to take a few months/years off between jobs living off of savings, and you've got a heuristic nearly as predictive of loan-repayment as all the rest of the information lenders use today put together.
