I understand what you're saying but ultimately it's still the investors paying Fitch. You can clearly see they have no quid pro quo with the company or product they are evaluating. All your saying is who's invoice the bill appears on but the company is not paying that bill. The investor pays through the acquisition.
There is no investor at this point. The mandate is made by a 3rd party that is expected to be neutral. The investor only appears after the entire thing is settled.
Yes, it's not a case of fraud. It's a case of a process structured in a way that facilitates fraud. (Who pays for the invoice has the power to negotiate its value.) It is a very different thing, but it's still a problem to be solved.