I read it and trying to remain objective I can see where the PR Manager would be getting upset (No escuse for his poor language or antagonistic behavoirs)
I can also see where the buyer would be quite upset. However I believe he should have wrote a clear and defining email to start with the sum of his questions and inquaries.
I would say both sides where in the wrong essentially due to poor communication skills and the lack of considerence to the other person.
The later emails from the PR manager however VERY rude abrasive and uncalled for.
Just my thoughts