Except there was no shortening of life, so it's wrong. Don't base your theology on translations or Christian commentaries. All translations and commentaries are biased.
That said, before the other day when you raised the question, I've always just taken Genesis 6:3 to mean that God shortened human life expectancy, and I've never looked it up in a commentary.
Anyway, thanks for alerting me to the alternative. I don't think I can explore it further at this time, as attaining the required linguistic skills is a bit "out of scope" for me at this time.