The fact is that even if Davis' immunity had been of the weaker "consular" type he would still be immune from jail and prosecution under international law. That's because Pakistani police on the scene acknowledged that the men he killed were known criminals and one of them had pulled a gun on Davis before he was shot by Davis. No further investigation is necessary; such killings do not meet the "grave crime" murder standard, but are at most manslaughter.
Qureshi surely knows all this. So the implication is just what you wrote, that he is manipulating Pakistanis through the anti-American media to gather political support. Are you really going to let yourselves be twisted so easily?