I figured that they may have started at 3k until icon range but they could just as easily not have as you say.
You could well be right about foul play.
I am purely discussing the ACMs shown, I have no desire to be personally affiliated with either side of the argument. I think Gunzo was lucky because midway got some good hits although only .303s. repeated 10 times midway would have scored some damage with that solution 50% of the time. A few pilots would have made that shot look easy everytime.
However, the method of rope a dope is as old as air combat itself I should imagine. It is extremely reckless to get caught in such a way. Supposing there was no foul play in the merge then there was nothing wrong with this method of killing. Not the most glamorous method or much of a display of skill, but falling for the oldest trick in the book is not the fault of the roper but the ropee.