To be fair to Mats, I think he was a fully qualified engineer in Sweden. He was quite unreasonable in insisting on calling himself such in Oregon, but I suppose reasonable men don't change the world.
I also find it intriguing that all of the Professional Engineers in Oregon, including ones involved in setting up the timing on the aforementioned yellow lights, failed (or chose not to) solve a basic kinematics problem like Mats did. Why did it take someone who was not a PE to fix this issue?
I didn't realize that one's knowledge and skill is a function of location.
Different locations have different engineering codes. This is in part why US states do not recognize each other's PE assignations.
I can understand why he couldn't be hired as a licensed engineer because of that, but that doesn't make him not an engineer. He wasn't arguing over something that relies on local standards anyway. A second is a second regardless where you are.
FWIW, there are different types of seconds. Eg, Universal time seconds based on the Earth's rotation, and atomic clock seconds based on consensus. And leap smear seconds are variable length seconds to help merge one into the other. https://developers.google.com/time/smear