I don't think the audience can be a factor. After all, you can't see them, and there is no rating system to block listeners.
However, a lot can be derived from the delivery of such information. The emphasis and voice used can make a huge difference. If you read out a letter, and make no comment about it, it's kind of implied that you agree/support the letter. You are hardly going to read out a letter you don't agree with without commenting.
Also there is history. There is a way in which a presenter is perceived, and an image built. Opinionated/political/comic/shock/smooth etc etc. This can also alter the perception of what is said.
Australian radio is normally pretty keen to avoid the kind of comment that Jones supported on that occasion. Unfortunately there are many people out there who rely on single sources of information to form their own point of view. Also unfortunately, your average punter spends little time accessing decent quality, unbiased (as you can get) information. Ch7,9, & 10 news are still the most popular sources of news for Australians, and yet (at least to me), are alarmingly shallow.
http://en.wikipedia.org/wiki/List_of_Australian_television_ratings_for_2006