I dunno really. While, yes, I do think he acted unprofessionally.
Can you imagine how pissed off the guy would be at this stage? This likely isn't just one random email he's received, at this stage, he's likely got an email from most of the people who were ordering the controllers.
Each one asking in a variety of anger as to when their order will be here, and it's his job to answer each one as delicately and responsibly as possible. All the while due to unforeseen situations, the whole stock isn't delivered by the date he set and the company is likely losing money.
So, basically, what's happening here, is a guy who has a complaint is pushing it slightly and in response the guy is snapping.
Unprofessional, yeah, but, it's kinda sad to think that this guy is likely to be out of a job due to this.