To you, maybe, but to the law?
It seems to me that an auditor's report is expected to be, is intended to be, and follows widely-accepted procedures (GAAP, for example) necessary to be a statement of fact.
If, on the other hand, the ratings agency's report is expected to be, and intended to be, a statement of opinion, even professional or expert opinion, then that's entirely different.
If I'm selling statements of fact that are not actually factual, then I'm committing fraud. Free speech doesn't even enter into it.
But I'm selling statements of opinion, then regardless of the quality of my opinions, I would expect that questions of free speech should at least be considered.