In a letter to Major League Baseball obtained by the Los Angeles Times, developer Rick Caruso and former Dodgers Manager Joe Torre explain why they won 't continue to bid on the Dodgers:

Since the outset we felt that operationally it would be impossible to effectively manage baseball operations having the parking lots around the stadium under separate ownership. ...

It has now been made clear to us by Mr. McCourt that the lots are not for sale. Read the full text of the letter here.

As CurbedLA notes, McCourt made his fortune in parking lots. In 2006, he set up a firm called Blue Land, which owns the parking lots and rents them to the baseball team.

So McCourt can't be forced to sell them.

Bidders were told they could keep the lots in their bids if they wanted, but if McCourt decided not to sell they would have to lease them back. But many had hoped he would be persuaded to do otherwise.