It seems like people got the notion of the precontract the other way around. When words of a 'precontract' came out, people thought that Ferrari had the option of Kimi being taken into the team only if Fernando leaves. It turns out that the option holder was Kimi himself, contingent on Lotus sorting themselves out!
I thought it didn't make sense if Kimi signed a precontract where he could be left in the lurch - it indeed didn't turn out to be that way, he was holding most of the cards all along.