So does every other wikipedia clone site. But that's besides the point, he claims that mahalo is built with their users' content, clearly that is not the case.
Let me guess... Linux distributions are "stealing" Firefox? Oh, there isn't some holy war against that, so it's a good thing. Right.
It is perfectly compliant with GPL/GFDL to take the product and fill it with ads. There is nothing wrong with doing that.
The liberal licensing of Free software/content does not mean every use of those freedoms is a good and positive thing. And nobody is being inconsistent by treating it as a bad thing, while still recognizing it's within one's rights to do.
The fact that they attribute it is nice but does not detract from that point.
JC is on the record stating more than once that mahalo.com is built using user supplied content, he seems to have stretched that definition to now include the content of other sites as well.