But it's not a business and that person wasn't a customer. Debian is a community, bound partially by common technical ideas about packaging, stability and security, and partially by philosophical ideas about Free software.
Their goal is not to satisfy everyone who comes to their mailing list, that would be insanity.
Sure, but most people would consider the original poster's request as quite reasonable.
Instead of considering it in a balanced way and producing a polite & considered response, the response was idealistic rhetoric. For better or worse, I think that does qualify the attitude of response as "unprofessional", as stingraycharles pointed out.
I think Google is more or less "in the wrong" too, but a less snippy, snarky response would probably do more to convince people of that. "You catch more flies with honey than with vinegar", as they say.
Their goal is not to satisfy everyone who comes to their mailing list, that would be insanity.