Speaking from experience leaving a successful company with huge revenue and profitability(?) to a non-critical path role (I assume he didn’t join perception team there or something) in a company that has no real customers beyond some PoCs can be a huge culture shock.
The comment about safety is obviously tongue in cheek
I know that sentence was probably meant to be humorous and not taken too seriously, but it comes off as smug and disdainful. Manufacturing is very difficult, and road safety is anything but trivial.
He joined the company because he believed in the mission, but then decided the lifestyle tradeoff wasn't worth it? His conviction must not have been very strong to begin with.