The issue with salt is that it is stored with the password hash. So you'd pretty much get that information with the password. It's only designed to make sure the hash won't be the same for the same password on other users, not to make breaking the hash any harder on its own.
You could store it (and/or pepper) wherever the password is actually checked and splitting it would help. But I cannot imagine they're doing that. It's far more likely they're encrypting the password and keeping the key off the database server. Meaning they need to get both, to get passwords.