Then if the Django IRC channel has banned Mibbit, I suggest you speak with them -- assuming Freenode decides that expending volunteer services to support a commercial service is a worthwhile venture.
Otherwise, there's the freenode web IRC interface.
You just said you would pay attention if someone "with a genuine stake in the project community complained". And then someone did, and you brushed him off.
"Our channels". As I've said before, we've been forced to regularly ban Mibbit on our channels (as in, software projects with which I am involved). I simply don't represent freenode, or django, or web developers in general.
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I see Mibbit fans are downvoting any negative comments en masse, not to mention the vitriolic dialog with freenode staffers on IRC. Yeesh.
Otherwise, there's the freenode web IRC interface.