The murder charges are not all that he faces, he also faces charges of high treason. Also some other serious charge for the sacking of judges. And he is a declared absconder in another court.
If he returns to Pakistan, he will have to spend every penny he has and every second of his remaining life in courts defending himself, assuming that he has the legal acumen to not go to jail or be executed. There is going to be so much litigation against him that his grandkids will need lawyers. I very much doubt that he will return, under such circumstances. He may not have been very bright as a military general, but he should be bright enough not to step foot in Pakistan for the rest of hi life, or unless the winds of power change again there.
I am willing to bet that somebody will advice him against this (as the ISI did previously), and he will backtrack on some pretext.
Process for high treason case against Musharraf begins | Pakistan | DAWN.COM