I, for one, would like to thank Steve for saving my desktop from Mac porn apps.
Apple is a minority player in computers, there isn't going to be a chilling effect even if they did something as monumentally stupid as only allowing apps installed via their Mac App Store.
* The market is currently validating their stance of no porn on the iOS App Store with quite good sales.
The danger comes partly in the so-called tyranny of the majority. Just because the majority prefers something over the minority doesn't necessarily mean it's right. Also, just because the iOS App Store has a heavy-handed approach to adult content and yet it's doing well financially, it doesn't mean (1) that it couldn't do even better if it didn't have the heavy-handed approach, and (2) that all markets/channels should adopt the same approach. Those conclusions just do not follow, in my judgment.
Also, while Apple does many smart things, they are not perfect. I would not rule out them doing something you or I might consider as monumentally stupid. They are human. They make mistakes, and they have a different perspective, and their interests are not always aligned with ours.