The claim upthread is that regulation in labeling would materially curb fentanyl deaths. It would not. Materially restricting access to high-test opiates might, but we have ample experience from well-labeled high-test opiates to suggest that uncontrolled access to any of them is likely to be deadly.

If by "regulation" you mean "restriction", then, sure, I buy that, stipulating that it's somehow possible to restrict access. But what the preceding commenter meant by "regulation" was labeling. No, that won't work.