Ah! The old smoking gun thing again, eh? If by smoking gun we mean a clear and unambiguous accident cause, then no, of course it wasn't. Likewise the infamous Chinook FADEC wasn't a smoking gun, nor the known phenomena of UFCM's, or control jams in one, two, or even all three axis. So we shall never why ZD576 slammed into a Scottish hillside taking all 29 lives with it. What we do know though is that it was Grossly Unairworthy, and was known to be so. That is what these accidents have in common. Both aircraft were in contravention of the UK Military Airworthiness Regulations, and both suffered unsurvivable accidents costing 31 lives in total.
As an aside, are we to believe that there was no crew action that could be taken to ameliorate the danger of a blue on blue had they known that they had an IFF failure? I find that hard to believe, but there again I was never a roughty toughty type and await clarification from those who are, or were...