I'm not sure I agree. Going public benefited two groups of people:
1) the already filthy rich descendants of the already filthy rich founding fathers and;
2) the managers and supervisors who were rewarded with stock and "hypo-loaned" their home, wife, kids and collected beer cans to buy stock when it split (like rabbits).
3) The PTer and FTer that buys $50 of stock every payday really isn't benefiting as much.
WTF) Going public had nothing to do with 1997.
I will not argue with your first three points.
However, I know that 1997 strike changed many of the Board and all of the Management Committee minds.
UPS would have gone public at some point but not in 1999. My hypothetical guess would be maybe 2005 or so.
In 1998, there was a whole lot of talk how the strike had changed things ... I bought $100,000 worth of UPS stock
in 1998 based on the rumors (that's not insider trading BTW).
I hypoed a total of three times to buy UPS Stock.