The real sweet spot for Amtrak are trips between 50 and 200 miles. Within a city, subways / light rail are a better option. Longer than that and air travel starts to look better. Many cities also have regional trains that serve the areas between 10 and 50 miles outside the city.
This is how every city in Europe works. There are only a handful of cities in the US with a well-developed rail network -- and most of those are crumbling due to half a century of under-investment.
With high speed rail, the kind that other countries have plenty of, the sweet spot for rail would extend much farther than 200 miles. Tokyo <-> Kyoto, for example, is around 300 miles and is solidly still within the range of rail being a much better option than flying.
We can argue the exact distance, but it is details. His point is correct: rail makes sense for cities that are not very far apart. Rail trips across continents doesn't make sense (except as tourism).
That isn't to say you are wrong, just that you are changing the subject.