For what it's worth, 4QcommGen A (4Q252) understands Gen 6.3 quite clearly
as a reference to the remaining years before the flood. After 120 years,
the scroll appends AD QC MY MBWL.
> Quite apart from the context of 6:1-2 which bristles with difficulties,
> verse 3 is not without problems. YaDoWN is from root DiYN [=DuWN] to rule;
> compare the noun 'aDoWN, a lord. In 6:3 it is in the Qal; in the Niphal it
> means to strive. But to be lord implies also to judge; here the judgment
> is to
> reduce the lifespan to 120 years (or the time left for repentance reduced
> to
> 120 years).
Incidentally, MT's YaDoWN appears in 4Q252 as YDWR from DWR, "to dwell."
David Miller
Ph.D. student, Biblical Area
McMaster University