Why stop at financial products? If a celebrity advertises a car as safe and then someone close to you dies in a crash, should you not hold that celebrity accountable? Why didn't they look into all claims about safety of those cars?
I was proposing you ban endorsements of financial products so that it would not be possible to sue someone for later wrongdoings by that company. Once you have explicit rules for what is legal and what is not (there are already these rules) then it eliminates any confusion of whats illegal if you are a public figure.