Respect in this case, or the principle of charity if you prefer to consider it in those terms, requires acknowledgement of the fact that such intemperance of language from a customer almost certainly originates in extreme frustration provoked by the malfunction of the product.
In the course of a year and a few months spent doing credit card Tier 1, taking on average about 150 calls per day, I dealt with a lot of people. A very few of them were indeed just assholes, of the sort who'll open with "your product is a piece of shit" just because that's their attitude in general. They were easy to identify, but hard to work with. A vastly greater number were instead moved to unusually assholish behavior out of frustration with the situation in which they found themselves. Given a touch of professionalism, they were easy to identify, too, and easy to work with as well once given the opportunity to vent some of their ire and settle down enough to behave rationally again.
Perhaps the customer in this case is just an asshole. But my experience, which is not inconsiderable, shows that that is extremely improbable. Given, as I mentioned before, a touch of professionalism on the part of the support engineer, I see no reason to doubt that this situation could have been brought to the same sort of mutually successful outcome which I so often produced in my time wearing a headset all day. Instead, the engineer has succeeded only in producing a PR nightmare for his company, and I hope also in getting himself fired for cause. (I would! On the spot, in a heartbeat. Just as, in any of the several customer-facing roles I've had, such incredible behavior on my part would certainly have incurred the same response.) I fail to see how such an outcome has any utility for anyone involved - the customer's still stuck with the same broken product he started out with, and the company's out both money and reputation, too. I'd be fascinated to see how anyone could argue that that's a reasonable expenditure to buy a mean and fleeting little moment of satisfaction for one support engineer.