The pchar message headers were changes AND a new genesis block was created. So there's no way that the old fairbrix client was the culprit. It is possible that this chain reorg was accidental, but not likely. Anyways, it seems like the overall network hashrate has grown and it's harder to pull off this attack now. And given that fairbrix has no value right now, it's not really worth it to keep attacking it.
Then it was never worth it to attack it in the first place. Why would anyone pursue such an attack when there's no exchange? The only reason I can think that anyone might want to attack it would be in preparation for attacking tenebrix, which you can exchange. Maybe some of the RS/CH sycophants were a little worried
Still, I'd be willing to bet that it comes down to an accidental fork. Has anyone done any real investigation of this yet?