Does the appointment carry with it a fourth star? If so, Senate is required to confirm flag officers. In this case, the MACOM appointment may be a 4-star rank, so they have to promote him before he can become the commander there. I'm not sure if the appointment is a 4-star billet, though.
He may be up for a fourth star, but I think a LTGEN. can have the post. Central Command requires a 4 star I believe.