"I found 4 or 5 incidents of pilots deliberately flying aircraft with passengers into the ground over 30 years. I haven't tried to figure out how many fatal accidents there've been amongst airlines during the same period, but I know it's way, way more that that. Pilot suicide causes a tiny proportion of what is already a tiny number. "
I'll say it again.
There are very few instances of airliners being lost in the cruise with no immediately apparent cause. Of those, the instances of suspected deliberate pilot action form a significant fraction.
There is no statistical argument against it being a possible cause in this case.
No. It is of course a "possible cause." But there is an argument against it considered being
more likely than other highly improbable causes. The difference between 1 occurrence in 1 million of explanation A and no occurrences of Explanation B in the same one million is not significant enough to make predictions about whether A or B is more likely to have actually happened in a given case.