Immigration is one of the "revealers" of supremacist ideology: people are progressive until it comes to being progressive about borders. A lot of the US left are doubling down on "educate our nationals first" to disagree with elon, while clinging on to the implicit desire to see US supremacy maintained; which is ironically the same reason Elon is giving for skills-based visas. Both are aimed at maintaining global hierarchies instead of dismantling them.