Correct. I think reversion to the mean is a non-sequitur here. Neither the GP's quote, nor the OP, are making the statement "I understand that this mistake was

Correct. I think reversion to the mean is a non-sequitur here. Neither the GP's quote, nor the OP, are making the statement "I understand that this mistake was an outlier, you'll probably never make this mistake again if you remain unchanged". The claim being made is that acknowledging the mistake and learning from it can dramatically reduce the base probability of such mistakes happening again.