I think the mechanism is a bit different than what you described... if it's a user who wants to answer a question, why would http://www.mahalo.com/answers/education/does-anyone-have-any... have no answers?

From the same page: Did you ask this question via Twitter? We create a Mahalo account for everyone who asks a question via Twitter.

So yes, the tone of the blog makes it sound like Mahalo is scraping from the web, because Mahalo's pages make it sound like they're scraping from the web.

It's really not an issue about copyright as it is about plagiarism.