[JamesVI]

The data they present doesn't support their thesis (or the headline).

All the data says is that 50-60 year old non-managerial employees at tech companies are paid less, on average, than 40-50 year old non-managerial employees.

The simplest explanation is that the higher paid employees are retiring early because they can afford to (or even voluntarily moving to lower paid positions with less responsibility/more interesting work/fewer hours).

Everything else in the article is wild conjecture with no supporting evidence.