Although I'm not taking a position on whether the numbers are correctly reasoned, I think evaluating the value of the noncompete after the fact and as a static

Although I'm not taking a position on whether the numbers are correctly reasoned, I think evaluating the value of the noncompete after the fact and as a static value (was his domain knowledge worth $90 M) isn't likely how it was thought about. It was probably looked at as insurance against a catastrophic tail risk, the existential threat to the whole Android ecosystem. It might have only been a 10% chance that he could have blown up Android by going to a competitor, but insuring against a 10% chance of multi-$B loss was worth $90 M (for example).