Such things are encouraged by the excel UI because it fails to make relationships and manual corrections easily visible. The human computer interface matters beyond UX.
That isn't to diminish when Excel's help has disastrous consequences, but rather to say it shouldn't be unexpected. If your data requires precision, there are better tools than Excel for working with your data and there should be steps taken by more experienced members of the team to ensure the team doesn't get bit by Excel's features. Excel's behaviors are well known and I'd have to imagine at least one member of any research team has been bitten by Excel's assistance features before during research. I would be surprised if any serious educational institution that teaches about ethics and common pitfalls in research *didn't* caution about how Excel might corrupt research [0].
0 - Okay, maybe not _that_ surprised, but I would be disappointed and think less of the institution/instructor.
In combination with the (reportedly)blatant lack of any reference to the methodology in his paper this feels like wilful gross misconduct in professor-land.
IMO this sort of thing rightly undermines confidence and credibility of research in a much broader context and should be a sackable matter if shown to be true as asserted.