I think he was looking for Law whose crew was on Zou and he was looking for revenge.Jack was looking for MoMo ofc.
I can see that oo. But wouldn't he have attacked an injured Law after Dressrosa rather than taking on an Admiral and former F. Admiral trying to rescue Doffy? Then again, maybe his mission to rescue him took priority over a revenge.I think he was looking for Law whose crew was on Zou and he was looking for revenge.