If you were a client of Mt Gox and you were a victim of the Mt Gox "steal", you are looking for the one who stole your money. Now someone (CSW) pops up and says he has now the money which was stolen at Mt. Gox, you could indeed sue CSW at your local court to hand out the privkeys to given address (which he can´t, but hey...)
This guy is stupid, if it's established that the coins are his then every prosecutor chasing mt gox is going to sue his ass off to recover the stolen money from him.
Then again, I wonder if he will also claim swiveled FTX addresses belong to him as well.