Lets consider a hypothetical situation where there is a network split for one hour and there is a temporary fork into two equal size independent networks. In each of these networks validators will do voting for competing checkpoints. None of these checkpoints will be justified, since there will be not enough voting power for a supermajority vote.
Then after the network is fully connected back again, validators will have no way to revoke the votes. So there will be a large gap of one hour with no supermajority links, and the easiest way to bridge this gap would be to form a very long supermajority link that goes over the gap.
I am a bit confused on how this link would be formed. After the network is back fully connected, the validators need to go way back in time to one of the last justified checkpoints before the network split, and vote for a link that crosses the gap. It is not clear to me how this algorithm would work exactly, because, the validators do not per se know if there was a network split, and that the network is back again. The target of the gap-crossing supermajority link would have to be after the split, and since validators do not know when did the split end, they could only try randomly, which seems like a lot of chaos to me.
During the split, the validators would presumably keep trying, so after the network is reconnected there would be lots of competing minority links that have no chance to become supermajority links and originate from the same justified checkpoint that was justified just before the split.
Note that PoW handles this situation gracefully - after the network is back to normal, the trees are merged, and the strongest wins.