I have never heard anyone seriously suggest that the US shot down the Iranian Air Bus as a warning to the Iranians.

That is outrageous and should be taken back pronto.

The Air Bus was flying toward a US military vessel with a full crew, and the captain was obligated to protect his men.

The Iranian aircraft was spotted on radar, not by sight. It was warned repetedly to turn away, but it's radios were tuned to civilian bands, not military radio frequencies and did not respond. The US captain never recovered completely from the shock of what happened. To say this act was intentional is an outrage.