"A method for shaking down companies about to IPO by surprising them with some claim in the hopes that the company will pay to make the problem go away without fighting the claim"
I don't buy it.
well this is like that, and its timeliness is actually the point. this is the process for which the IPO holders signed up. and at least part of its legal justfication is to not have entities offer ownership up to the public, with which ownership shares undisclosed/unknown debts, liabilities, or obligations could follow. it's certainly not a conspiracy.