Andy, I agree with your point that people have to be cognizant of just how deleterious Zia ul-Haq’s role was. The Islamists whom he enabled to enter the military are now colonels and above. And, you are correct at how he channeled aid in Afghanistan: He was so afraid of resurgent Afghan nationalism (the Pushtunistan issue) that he supported the Islamist groups in Afghanistan exclusively and sought to cut off nationalist groups. When folks in Washington made the decision to aid the Afghan resistance, they had no choice but to work through Pakistan, as access via the Soviet Union and Iran were both impossible. The point to draw out is the drawbacks of multilateralism: When working in a coalition, every partner preconditions its own role and sometimes those compromises contribute to blow back. Multilateralism may be mantra now, but policymakers should be cognizant of its costs.
I go through some of the background history in this 2002 essay.