I think that was in the context of leaving a big company to start a startup.
Joining a big company after your startup is acquired is a bit different dynamic. Maybe it can be likened to opium. I've never tried opium, nor sold a company.
But it must feel good, with obviously bad and brewing side effects.
They might have wanted to leave for some time.
edit: It's really close to the exact 2 year mark http://www.crunchbase.com/company/last-fm