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.
He can almost certainly make time for spite.
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.