Would it be reasonable for some normal people to assume that somebody who runs a business has more intimate knowledge of risks associated with the business than some external party especially when the person running the business is also claiming to be a specific expert on risk assessment?
In general, yes, but that didn't actually happen in this case. At least, I very much doubt it did. If anyone wants to come forward and say they considered Patrick an expert on risk assessment and took his ratings seriously, I'll reconsider.
If someone did rely on that and can make a case that there reliance was reasonable under the circumstances, that would certainly weigh towards assigning more liability for losses to Patrick. To divide the loss, you have to look at the facts and circumstances of each individual loan. I doubt that was a factor in the loan that started this thread, but who knows.