That was 1 or 2 crews that couldn't be forced to move or commute to Washington State so other crews could get more training.

Can an Amtrak engineer quickly relocate from NYC territory to NP territory? Aren’t the signal systems still very regional?

For a company the size of Amtrak, a one day event has zero relevance to anything on the opposite side of the country. It's not like the crews were qualified on a piece of track 3000 miles away.

I don't believe Amtrak can force T&E crew to move cross-country, although outside of the Auto-Train contract (totally separate seniority and work rules agreement) crews may have nationwide seniority. They could probably give incentives for crew to transfer, either temporarily or permanently, to correct an imbalance. CSX was doing that on a regular basis right after the Conrail split. I worked with quite a few temporary transfer engineers from the South in the first year after the split.