Stossel is the one bulwark against all-left all-the-time big three network journalism. ABC tolerates his opinions and reports because they are very popular and he is an entertaining guy. He is a libertarian, and is just as likely to bash the "religious right" as government waste and junk science, which, IMHO, makes him tolerable to the net heads. If he was someone with a purely conservative point-of-view, they wouldn't give him a soap box in prime time.
True, ABC does have George Will on Sunday mornings, but in their many hours of newsmags per week, it's only Stossel with his five minutes or so of "Give Me A Break!" to balance ABC's left-leaning heavyweights (Jennings, Walters, Sawyer, etc.).