You go on PSN, then you are subject to Sony's policies and they can do whatever they want. However, it's the consumer's hardware and Sony has no right to tamper with it outside of their network.
When you buy hardware, you buy a physical device and I don't think they should be able to tell you what to do with that hardware. But buying software is buying a license and then you are subject to the developer's terms. I know some will disagree with that viewpoint, but that's always been the way I have interpreted buying hardware and software.
However, what matters is how the law interprets it.