Avatar and personal text campaigns weren't really a thing when this campaign came into being, so it's possible that wasn't considered when they made the rules.  Due to the fact that the campaign is largely automated, it has no way of detecting what your avatar and text says, so in theory it would still pay you.  But whether or not it's within the spirit of the rules is another matter.  If the people running the campaign decided they don't want people renting out avatar and text space as well, they could potentially throw you off the campaign for it.  I'd say fire off a PM to the OP just to be on the safe side.