Their thesis was that
- startups would remain private longer.
- employee's lost their options when they leave
- longer periods to go public means more employees return options to the pool which means employee option pools can be smaller
- longer private periods leads to more rounds raised which benefits investors over employees as the former can participate on each round to keep from being diluted
- exits would come eventually and the investors would always have superior terms, I believe that they were working under the assumption that investors would never have mandatory black out periods after IPO so they could essentially participate in the opening day IPO pop.
This is one of the coolest and most maddening things about finance. Every time you think you've come to a big realization, usually you find out that someone else came to the same conclusion many years ago and has been making money "arbing" it out ever since.