The author is pointedly ignoring an obvious and legitimate possibility, its as simple as that.
It's only a "legitimate" possibility if you think the separatists, who bragged about it publicly online, albeit thinking they shot down a Ukrainian cargo plane, took videos of it, and are also captured in intercepted conversations admitting to it, and who, with the Russian govermnent, are currently lying that they have Buks (or had, they've been sent back to Russia it seems), are also under Ukrainian control. At that point, we're in cookoo land accusing Strelkov and his murderous goons of secretly being CIA or SBU agents, rather than Russian ones.
With the piles of evidence, and the piles of dead bodies, it is not "legitimate" to propose "possibilities" that fly in their face.
Ukraine accidentally shot down a passenger plane in 2001.
They have the Buk missile, in exactly this area.
If you want to write an article that covers “everything we know about the theory a Buk missile shot down the plane”, it is a gross omission not to mention these facts.
If the plane was an accidental shooting down, how can anyone justify a stronger punishment than was given to Ukraine when they accidentally shot down a passenger plane in 2001?
Wouldn’t it have been common sense not to overfly a warzone, a tiny part of Ukraine, which is easily avoided?