So the Ukrainians somehow misidentify a 2 engine Boeing that has flown over the length of the country for a 4 engine Ilyushin that looks nothing like it.
They don't pause to wonder why Putin would be flying over a war zone.
They don't consider what the disastrous consequences of killing off the leadership of the Russian Federation would be for them.
So they scramble not an interceptor, but the Su-25 ground attack plane, with a service ceiling 3000m below MH17, to do the job.
Then they simply fake the recordings and the web posts of the rebels saying that they shot down the plane.
Oh, and they get US and other Western intelligence to go along with their story.
Yeah, sounds legit.