Justice Kagan, if "some people like less prescriptive standards" why haven't any members of the regulated community said so in San Francisco v. EPA?

Today the United States Supreme Court heard from lawyers representing the City and County of San Francisco and lawyers for the United States Environmental Protection Agency on the question of whether a “narrative standard” can be enforced in a Clean Water Act NPDES Permit.   When San Francisco first sought the Supreme Court's intervention in this case I predicted yet another loss for EPA in the Supreme Court. 

The narrative standard at issue in this case, and many others, is that the permit holder cannot “cause or contribute to violations of applicable water quality standards.”  

The last time EPA considered a Clean Water Act case, in Sackett v. EPA (which was also an appeal of a Ninth Circuit decision), the Court held that EPA's (and the Ninth Circuit's) interpretation of the term “Waters of the United States” in the Clean Water Act was “hopelessly indeterminate” in the face of the due process requirement that penal statutes be defined "‘with sufficient definiteness that ordinary people can understand what conduct is prohibited’ and ‘in a manner that does not encourage arbitrary and discriminatory enforcement.’”

Because there is no way that “cause or contribute to violations of applicable water quality standards” is any less “hopelessly indeterminate” than what was EPA's definition of “Waters of the United States” before the Supreme Court stepped in, and the penalties, and opportunities for citizen suits, are as potentially draconian for violations of NPDES permits as they are for violations of “dredge and fill” permits, I've always thought that the same six Justices that ruled against EPA in Sackett will also rule against EPA here. I'm a little less sure of that prediction now but I still think EPA ends up on the short end of this stick.

Justices Sotomayor and Kagan dominated the questioning of San Francisco's lawyer. Justices on both sides of the ideological divide were more involved in the questioning of EPA's lawyer. Predictably, Justice Alito raised the penalties one might suffer for violating the “narrative standard” and Justice Coney Barrett also asked about that. Of course Justice Alito is the author of our nation's highest court's opinion in Sackett striking down EPA's definition of “Waters of the United States” for the same reason.   

The most surprising suggestion I heard was Justice Kagan's suggestion that “some people like less prescriptive standards” like the “cause or contribute” narrative standard.  Now I've only been representing the regulated community for three and a half decades but I don't know who these people are to whom Justice Kagan is referring. I note that the City and County of San Francisco are joined in this appeal by fifteen industry groups and dozen or so water supply and conservation associations. I don't see any briefs supporting the “cause or contribute” narrative standard from the regulated community.