That top bureacrats too afraid of Russian AA strike that forced pilot to fly as low as possible.

Yea, I suppose but for me this seems like a stretch, As you say it's pretty deep in territory, Russia has generally been from what I understand mostly active in the areas of conflict, kiev is not really currently that. Sure some missiles go, but not rockets.

I think your suggestion about a likely infighting between the evil in the hordes makes the most sense to me.