Actually, Sony's warm and kind to the homebrew community and have been since the days of the original Playstation. Stuff like NetYaroze and the PS2 Linux kit have always been supported by Sony. Hell, including direct support for Linux in the PS3 is proof of that. They know that people want to hack around and have fun on their machines and work on homebrew which is why they support it.

The reason why they are tough on the PSP is because, unlike the PS3, there isn't really a sandbox that the users can play in. If you are running homebrew, you are most likely running in kernel mode, which means you can brick your PSP if you run the wrong homebrew program. That's what Sony's main concern is. Containing piracy is also something they care a lot about, for obvious reasons. Because there's not really a way to separate the two on the PSP, they have to be covering everything just simply to protect their users and their licensees. Unfortunately homebrewers are lumped into it because there's no separation. Sony knows and is planning on fixing that... though it's entirely possible that it's too late for the original model. Perhaps with the new slim, we can have that separation and therefore they can allow homebrew.

Anyways... that's enough of a tangent.