Meh, it means that the guy sending the email is a bit loony. It doesn't excuse responding in kind. Karp and Tumblr are a big deal. They should set a higher standard for themselves.
I see, so the user is merely "loony," for mass-emailing the entire Tumblr headcount with his screed, but Karp is a mean and incompetent boob who should be replaced and [your favorite punishment here] for responding naturally to that situation? Karp's sentiment wasn't directed at all users, he was telling a loony to not be so loony, but loony man can't recognize the social cues involved and so generalizes Karp's response to the entire universe of Tumblr users. Loony.
Its not about standards. If this guy was at your doorstep whining like that, what would you do? I would get irritated and lash out also.
Its about implementing strategy for that.
"And this right here folks is why a startup is so extraordinarily stressful, why PR agencies exist, and why a squeaky wheel gets the grease." - Ramanujan http://news.ycombinator.com/item?id=2151989