For a researcher, the reputation matters a lot. One lie ruins the reputation. I read about PhD degrees taken away because of falsified or fabricated data.
I honestly opened the link you provided fully prepared to evaluate the methodology, look at the statistical analysis, check the hypothesis. But this research was done so poorly that I could not help but go check this person's biography. So yes, I checked the messenger - of course I did and gosh I'm glad I did!
And no, it is way more than accounting error that got him convicted. It is the pattern of behaviour.
He falsified data many times in his previous works, and his papers were rejected (not accepted to publication) and retracted (withdrawn from publication) because of him lying many times, again and again. It's a pattern.
Re: his PhD, if you follow the comments section in the RetractionWatch article from 2018, this Fleming guy himself came in the comments section to argue with people. But he never answered the simplest question "where did you get your PhD from?". He got MD and JD (from an online school) - that was verified, but he also claims to have a PhD which he could not say where from.
If that's the guy you choose to believe... ¯\_(ツ)_/¯