There's a "cheat" to avoid this situation in the technical spec[1]:
In case the MTP of the tip of the chain is 12h or more after the MTP 6 block before the tip, the proof of work target is increased by a quarter, or 25%, which corresponds to a difficulty reduction of 20%.
So as long as the BCC keeps lagging behind massively (less than 6 blocks every 12h) the difficulty is reduced by 20% after every new block.
In case the MTP of the tip of the chain is 12h or more after the MTP 6 block before the tip, the proof of work target is increased by a quarter, or 25%, which corresponds to a difficulty reduction of 20%.
So as long as the BCC keeps lagging behind massively (less than 6 blocks every 12h) the difficulty is reduced by 20% after every new block.
[1] https://github.com/Bitcoin-UAHF/spec/blob/master/uahf-techni...