Here are the achievement's requirements on patch 3.3.5a AKA on Icecrown :
https://imgur.com/a/5Gxex You don't have to be Honored with Bloodsail Buccaneers and Exalted with Steamwheedle Cartel(those 4 goblin factions) at the same time. Once you get Honored with Bloodsail Buccaneers, you get the credit and can skyrocket back to Hated again, you won't need to worry about that anymore. Just don't forget to take "Avast Ye, Admiral!" achievement while you have Honored, which is Feats of Strength achiev as well and will give you "Bloodsail Admiral" title. It's basically free now while you are friendly+ with this faction. Good luck! : )