CPUC would need to figure out a legal way of doing that.
Basically, the CPUC is only allowed by law to regulate privately or investor owned utilities. Public utilities are not regulated by the CPUC. A severance fee is levied upon IOU customers that are "allowed" by the CPUC permission to leave and that have their rates regulated by the CPUC when the customers finds another regulated utility to serve it.
Most state laws allow for a city to condemn IOU property and force a sale. In such a situation, the question is....does the CPUC have standing in the condemnation court proceeding and can the CPUC ask that charges be imposed to protect the "general public" when the condemnation laws don't speak to this kind of thing.
I believe that the battle over "exit fees" is still going on behind the scenes. From six months ago at the Califorina Manufacturers & Technology Association website:
CMTA is pleased the CPUC respects the legitimacy of direct access contracts entered into last summer. Large users entered into direct access contracts to avoid the outrageously high rate increases imposed by the CPUC. The rate hike for large customers ranged between 50 and 150 percent.The direct access decision by the CPUC now sets the stage for an even more contentious issue: the debate over exit fees. A recent Department of Water Resources memo estimates the cost responsibility of direct access customers for DWR’s revenue requirements at $23.95/MWh over 15 years. The key goal now for direct access customers is to ensure that exit fees are not prohibitively high so as to make direct access uneconomical. Thursday’s vote was a step in the right direction, but the battle has just begun.