Was I really out of line here...?

You have a point, but people are more likely to watch how they talk to people especially when they are at risk of being punched in the face.

 

So he is just another eBay widget mover...

...and an arrogant one at that.

Not to mention a complete jackass. I'll bet he shaves with a Gillette Fusion.

Man, you are nice. My reply would have started something like "Dear (bleep), Until I received your reply, I did not realize there were lifeforms extant with a lower IQ than bacteria...

... May you be devoured by a pack of rabid Chihuahuas,