There are several issues going on here:

1. There could always be more talent. And the more you have, the more you can use.
2. Calling this a "permanent shortage" however is suspect. That implies that other methods and processes can't be used to accomplish the same thing. Substitutions can be used to avoid shortages.
3. It isn't "excellent engineering talent" which sparked this debate. It is the low cost, generic, H1B talent used to suppress wages that sparked this debate.
4. Elon's remarks illuminated a serious disconnect in his thinking. While most of us think of America as the citizens of the US and believe the purpose of MAGA is to improve their lives, Elon's metaphor of a sports team (issued before this tweet) indicates he thinks of America as an economic engine where he can simply cut the roster and bring in foreign free agents.

My take is I don't care if stopping immigration causes America to fall behind India and China. Because that is not what MAGA's purpose is. Our purpose is to rebuild this country and bring it back to the ideals we once had, where citizens were proud to be a part of the greatest nation on earth. After that, the American spirit will allow us not only to catch up, but surpass anything the Indians or Chinese can accomplish.

Sadly Elon, in this sequence of tweets, demonstrated quite clearly he does not share that vision. For him, this is all just about how much he can extract right now to push technology, rather than how much he can improve the country and the lives of the American people.