The main issue, as per the OP, was the BoI report. Subsidiary issues, posted a little later, were:
Can anyone answer the following qusetions (1) At the time, did ZG710 have a IFF Mode 4 integrated failure warning feature? (2) If it did, was it audio or visual? (3) What pre engine start IFF checks were carried out by ground crew? (4) When did ZG710 have its last Major?
It seems that the answer to Q1 was no, it didn't. As to:
If I recall, air safety, which includes airworthiness, excludes the effects of "hostile action". You could argue the functionality of an IFF system sits both sides of the line here.
I'm not sure what you mean. Hostile action may well have caused the IFF to fail, if that's what you mean. Hostile action would not have then deprived the crew of a warning of that, for that had already been assured by its fit, unless you include as "hostile" the lack of "Duty of Care" by the Airworthiness Authority, aka the MOD, which I would consider a very appropriate comment, but I rather doubt that to be your meaning.
As to possible crew action had they been so alerted, I am indebted to both Courtney and you JFZ90 for your input. No doubt there were shortcomings in the Patriot end of the tragedy. There will always be such shortcomings in the "Fog of War", better then to make sure that one's own ducks are all in a row before they paddle into it, to grossly mix up the metaphors!