The global satellite system is not ours nor can we trust on it in the case of a war. Plus the GHQ, AHQ & NHQ are all the peace time HQs, nor will the while GHQ shift to E-10. AHQ is in Islamabad but many of the deptts are still working at the old location, same case with NHQ. in case of a war they would be nearly empty, we have a separate war time HQ (place & location unknown) from where the top hierarchy can control it & be safe.
So if GHQ is shifted, it will not be 100% to Isb nor is E-10 large enough to accommodate the whole of GHQ.