Just because it’s not mechanically automatic, does not mean it’s not a launch on warning system.
The key phrase there is “it does not rely on a launch-under-attack policy to ensure credible defense”
If the US detects a ICBM launch, it will launch a response. It does not matter if the thing that presses the button is a person or an automated program.
Launch on warning just means a country won’t physically absorb a nuclear strike before launching, but will launch if an enemy launch is detected. It has nothing to do with automatic launch systems.
200miles/8hours of skating straight means an average speed of 25 miles an hour.
Ambitious, considering the average speed of a skateboarder is closer to 10 miles an hour, but it could be possible if he was extremely fit, had unbreakable bones, and the US was a flat plane for 3000 miles like this guy thought.