This. You could believe that Mason was acting in a completely earnest fashion, but was too naive to realize he was being manipulated by Lefkofsky.
As Excutive Chairman in a non-operational role, Lefkofsky is under only a fraction of the unpleasant pressure Mason is under as CEO. If he were guilty of behaving in this way, that would actually jibe pretty well with pg's assertion about people not wanting to run struggling public companies if they can avoid it.
Personally, I am no expert on Groupon. I make no claims that Lefkofsky has behaved in that way, because I don't have any evidence to either validate or invalidate such a hypothesis. It's simply not clear to me that such an accusation is obviously false, as pg claims.