It will help would-be immigrants understand that the US does not want them and that it would be a mistake to invest time and energy trying to build a future in a country that hates them and can nuke their lives at the drop of a hat. It will help other countries that are not the US retain their talent and build up their own industries. A greater diversity and distribution of talent and industry across the world is a more resilient system.

I think the parent is saying it's good because immigrants will go elsewhere and the US will continue to decline. Which will be good for humanity.

It could be good for anyone country that's not the US (despite our hubris, we're not actually the center of the universe). But for the US, a country built on immigrants ands immigration, probably not so much. We fucked around, we found out.

Well, we're continuing to find out. We haven't exactly scraped rocked bottom yet.

Yes exactly. One country sucking up all the best talent is not good for the world, its a single point of failure.