>If litigants receive relief through a PI, it addresses their specific harm. Extending it nationwide may be unwanted if other jurisdictions have different views on the policy.

That doesn't matter if it's a federal issue (which it would have to be if it's in federal court). A single district judge dictating national policy temporarily, while a higher court makes its determination, is exactly what they're there for.

Either the activity is legal (nationwide) by federal law, or it's illegal (nationwide) by federal law. Limiting to the plaintiffs violates equal protection.