The rebels may have thought it was a military transport but Russian technicians would have known otherwise.
The plane was at 33,00 feet and 3 minutes from being in Russian airspace and out of rebel-held air space.
http://www.freerepublic.com/focus/f-news/3183467/posts#6
I can certainly see a bunch of yahoo rebels shooting down a jet if someone told them what buttons to press. The idea that Russian professionals were involved is a much bigger stretch. The plane was at 33k almost out of the country so transporting troops doesn’t add up.