Well they were reluctant a year ago and that's part of the reason why everyone was making fun of VKS.If Russia is so scared of a conflict with NATO that they are unwilling to shoot down a UAV, then they might as well pack up and go home.
I don't believe this is the case, hence why I don't understand their reluctance.
That's changes as of a few hours ago and the question is why. What suddenly gave them confidence.
At least from what we see so far US isn't calling for a military response just yet, so calling their bluff seems to be working.