The guy was a tool, you might get away with it, but it only takes having to do a recall ONCE to eat a hundred times any savings you might have made.
Also, even if it works today, it might not work on a future batch of notionally the same part, and the manufacturer will laugh at you.
The datasheet tells you what the manufacturer is prepared to put there name to, going outside datasheet means you have to do all the qualification on the parts yourselves (Including potentially per batch qualification). Now sometimes (Down hole, high or low pressure, cryo, some space) you have really no choice but it is always better not to go there if you can avoid it.