I mean, if the army personnel and contractors in charge of the systems that shot down the plane are like any other system experts I've seen, their first reaction to "Can this bad thing have happened?" is "No, of course not. It's impossible, there are contingencies."
And then they re-learn the lesson they should've internalized in their first programming classes: "yes, your systems can fail including in ways that you never imagined them to".
(ok, this is me assuming it was an automated strike, which I'm not certain of --- but the same kind of defensiveness applies to people too)