I didn't say one should assume it, just that many people do. "Chemistry researcher committed fraud" is simply not the same as "Dishonesty expert committed frau

I didn't say one should assume it, just that many people do. "Chemistry researcher committed fraud" is simply not the same as "Dishonesty expert committed fraud". You give an alternate explanation, but it's still an explanation; one which wouldn't be needed (and indeed wouldn't apply) to a chemistry researcher. A variation on your explanation might be: Dishonesty researchers discover just how easy it is for dishonest people to cheat the system, and how little consequence there is, and so is more tempted to be dishonest.