I've read your posts for years on HN, don't undersell yourself.
Many CEOs don't know what is their company's contracts, nor do they think about it. While it is laudable that you paid such close attention, the fact is I've met many leaders who have no clue what is in their company's employment paperwork.
I think that this clause is so non-standard for tech that it almost certainly got flagged or was explicitly discussed before being added that claiming that he didn't know it was there strains credulity badly.
Huh I should read mine.