Furthermore, take a moment to think about the hypothesis that a Ukrainian jet would fire upon a civilian airliner.
WHY? To sway public opinion against Russia? Public opinion was already against Russia. The Ukrainians know that the airspace is being monitored by US and NATO assets. They know that the radar intercept and tracking signals from a fighter jet are clearly different than from a BUK. They KNOW there is no way they would get away with a shoot-down.
So now you are left with the possibility of human-error/accident on the part of the (mythical) Ukrainian pilot. A highly trained pilot flying ground support/interdiction mission would not have any reason to approach, much less engage, an airliner. He's trained enough to differentiate between a great big fat-body passenger plane and a Russian jet. Furthermore, the airliner is squawking its status for all to hear and see and in no way resembles, visually or otherwise, any Russian spy birds. He, the (mythical) Ukrainian pilot, will have no reason to even “accidentally” paint the airliner.
Finally, if there had really been a Ukrainian jet in the area, the dumb-ass militia/separatists/terrorists/Russian pawns would have been arguing that they were aiming at IT and the airliner just got in the way. Instead we have intercepts of those same dumb-asses bragging about bringing down a Ukrainian spy bird.
They are dumb-asses. Barely trained conscripts misusing 1980’s technology = lots of dead people. Putin didn't order the shooting, but he put the gun in the hand of the perp and set him out to rob the liquor store.
What is the source of this information?