I have read of people doing MSE following jaw surgery but the preferred route is to do it beforehand.
I heard from one orthodontist who said it is potentially possible but it adds some complexities and a surgeon who said it can be done afterwards.
As you allude to there is some potential mid face expansion that occurs with MSE, how that expansion takes place exactly I dont know, but my understanding is that once you have the metal plates that are embedded in and around the nose and cheekbones, this may alter the potential for expansion later on.