Absolute total Bravo Sierra. Those airliners have exact departure procedures they follow with exactness. In a time of tension those pilots would be more than precise in following the proper procedure. In addition those pilots would be following commands from the Iranian Air Traffic Control. That aircraft was flying exactly where it was directed to fly.
There are only two logical explanations. 1. The person in charge of that SAM missile site screwed up beyond belief. 2. Iran wanted that airliner shot down for reasons we do not know.
In addition that 737 would be "painting" a radar signature that was unmistakable from a warplane. It was climbing out and away from Tehran. Its radar signature would be huge and unmistakable. Hundred of planes probably left Merabad airport that day. Why was this one considered hostile?
What you see is what I see.
That squawk set it apart.