If true, not likely that Rebels are manning it in my opinion, that kind of tech would be left to the pro's. Whoever did it, they would have nothing to gain from this. So a tragic error has been made by someone. IMO.
Ukrainian rebels will not have the technology to shoot down a flight at 33000 feet. Military flights generally fly at a lower levels, so easier to shoot down with shoulder mounted weapons. If indeed it was shot down at that height, only governments would have the technology to do this. Russia or...