If they did not complain when they were sent the letter (of vesting) either they did not care about the stock or was under the same assumption they were that is over 4 years.

Of course, contracts are legally binding, but that's completely different from my perception / evaluation of someone - if the mutual understanding was over 4 years and then 30 years later you find the typo and come back to bite me then yes it is 100% an irreparable relationship.

Yes I would think better of them if they came back to bite if NVIDIA was a penny stock but probably nobody would bite them back if they found out it was worth $100 instead of $1B.

To be clear, the grant is the legally binding document regardless of intent (initial offer + vesting seems to imply 4 years), I would eat the typo if it was 30 years ago and chalk it off as a learned mistake (assuming it wasn't company altering), although I would still think less of them for fleecing.

Unfortunately true.

I'm just differentiating between the legal correctness and personal opinion/viewpoints on the matter.

Regardless of whether you are legally correct or not isn't really the crux of the issue for me, heck maybe Jensen doesn't even care about a billion given everything's he's minting (who knows though).

I was only talking from personal standing, in your stated cases or if I was in this position (I made some assumptions regarding the case), it would be a breaches of good faith and I would find it hard to trust them in a partnership ever again.

Only my POV, maybe the folks at the B level don't care about this as much since they are starting to fling Ts around. I can see how some people wouldn't really care, i.e. treating them as a freelancer and main objective is getting something done, but on a personal basis probably wouldn't trust them (say on personal matters that are company defining).