There's a bit of a nuance here - his grandniece was killed in the Ethiopian 737 accident [1] so it's personal at some level for him.
[1]: https://www.npr.org/2019/04/04/709999296/ralph-nader-calls-f...
[1]: https://www.npr.org/2019/04/04/709999296/ralph-nader-calls-f...
HN is showing a trend of purely blaming Boeing, but there were in fact several failures. Any one of: pilot training [There's a runaway stabilizer trim procedure that's actually a memory item for 737 pilots], not allowing single sensor inputs for flight control systems [FAA spec failure], the decision to allow the MCAS system to command an extreme amount of trim [engineering failure, should have been limited to a sane value] could have prevented the accidents.