The fact that Kayani did not allow Mush to rig the elections (as much as he would have loved to) by ordering ISI and other army personnel to stay clear of the electoral/political process shows that he is also his own man.
We all know about Mush's 'chikkut' nature. A more pertinent Q to ask would be why has Kayani so far chosen to remain silent on the subject? Is this really simply out of deference for Mush or does he not care much about where he resides.
It has much more of a symbolic import than simply a matter of residence GA.