Earlier quoted context omitted.
They are full of it. There are pictures of Putin at Russian military bases standing in front of 9M38M1 missiles!
Obviously, I don't know who shot the missile. But when trying to use logic here, I don't see why would Russia shoot the plane. They had nothing to gain. Ukraine? I don't know, I refuse to believe they would deliberately kill hundreds for some advantage. My bet is on the rebels who did it mistakenly. The question is whose BUK they used. One provided by Russia or one taken from an abandoned Ukrainian base.
What we should remember here is that "who did it" in this matter is more a matter of who was in command and who provided the hardware, rather than who pushed the button.
This is the most likely hypothesis but there are others. Apart from the craft being downed by Ukraine (Nothing in the report points in that direction), another hypothesis one would be actual Russian personnel, rather than Ukrainian separatists, operating from inside Donetsk. That would be hugely controversial, but hard to prove.