If so, then removing the SALT deduction (if that is what caused him to move) is a good thing, because he will contribute more to the economy and to federal tax revenues.
If not, then removing the SALT deduction is a bad thing. He contributes less to the economy and to federal coffers. And this calculus could get worse if NY (and NJ) start leaning in to receive more federal dollars (in whatever form) to make up the difference.
The incentive for the NY'er to move is clear. Whether its a good result is another thing.