There are two possibilities here (assuming this isn't all just bullshit).

Floyd wants to fight Hatton because he would make a shit load of cash doing it in England, less than he would make for fighting Pac, but still a significant amount of coin. It is also a MUCH less risky fight (sorry Hatton fans).

OR

Like albsur says, PBF wants TWO big paydays when he comes back, Pac and Hatton. He won't let the two of them disrupt that, so he fights Hatton and then fights Pac.