It seems to me only logical that the entity that commissioned the work, invested the resources and made it happen ie the company should own the patent.
What you're proposing sounds like zero incentive to invent while being employed. Doesn't make much sense psychologically.
$8 Million is quite low if you know what this guy's invention stimulated across various fields
I think just is if one agrees with the employer about a certain split ratio when signing for the job. It seems that here in Germany while employed at a university the inventor is entitled to 30% of the revenue achieved by commercialization.