Before you have a regulation, you need to think about what the problem is to which regulation is a solution. You might think we need to regulate ratings because they disagree with each other, and that's bad. What is another word for disagreement? It's diversity. We can have legitimately different opinions on the ESG of a company, as we've discussed. There are so many complex issues here that it's hard to say what's green or brown. It's actually fine for ratings to disagree, just like Goldman Sachs and Morgan Stanley might disagree as to whether a company is a buy or a sell.
I'm not clear what regulation would achieve in that instance, because it's not clear what the problem is for which regulation is the solution.