Look at it from Ken's perspective though. He's one of the few people who have moved this field forward by solving very hard problems over decades.

Now a startup comes in and publishes a cool video that claims to solve a big chunk of what he wants to do / contribute to over the rest of his career, like "hey that was easy!".

He says the video is very misleading, and that's just a fact.

It's hard to see for someone outside of this how insulting that can feel to someone in his position, and that's why it can come across as petty.

Also, your summary of his criticism isn't quite right, read it more carefully. It would apply equally if an academic group had done that. It's more a case of academic standards for communication meeting silicon valley bluster.