Speculation: option pools (at least pre-ipo) are generally a fixed %age and therefore relative size. With fewer engineers the ones left get a higher piece of the pie? Just a guess.
Maybe there’s only 25% of employees left to share the pie, but the pie itself is now only worth $10B. That’s not a great incentive when asked to work nights and weekends on capricious initiatives that come and go.
"The H-1B program allows companies and other employers in the United States to temporarily employ foreign workers in occupations that require the theoretical and practical application of a body of highly specialized knowledge and a bachelor’s degree or higher in the specific specialty, or its equivalent."
Note, among other things, the word "temporarily" and the phrase :highly specialized knowledge." The real problem is that H-1Bs are often used by companies in very different ways than their stated purpose.
Stock options could have a strike price of whatever, but tax favored stock options need to be granted at fair market value. Granting non-favored options away from FMV needs to be treated as immediate income, which is messy.
In actual fact, excepting "cultural loyalty" (which is usually interrupted in any such large acquisition/disruption event) essential employees are typically the most transient/difficult to retain. Many are not as remuneration-driven (more likely to be comfortable & their competence is often driven by a more vocational motivating factor) & even those who are can negotiate good terms elsewhere with relative ease.
This leads to a concentrated brain-drain where the fewer engineers remaining to partake in the pie aren't contributing as much value. That ain't protecting your core.
He can almost certainly make time for spite.