@tdracer
Plausible, and it reminds me of the paranoia during OEF (2004ish) regarding how many Stingers were left over from Massoud and his allies fighting the Russians. Once you give it to them, they may use it in ways you didn't intend.
My point is that I don't think any Russians pulled the trigger. However, the evidence trail may lead there (per Lena.Kiev's point).
For the industry, I would hope that the lesson learned by airline management, and perhaps even national authorities, is to give war zones a wide berth due to the lethality of modern weapons.