I have in fact done this, and it did ruin the motor. Ran Jet-A through a two stoke motor in an emergency, and while it did run, thick black oil poured out of the exhaust until it quit. Piston and cylinder were scored badly.
I don't doubt that.
But... There is a difference in using the wrong fuel by mistake then doing something about it and running the wrong fuel 'til she blows.
In your case I guess you didn't have a choice.