I think this would help everybody out on both sides and I think Sony could make money by using a trick from the music industry on this one.
Everybody (who plays or wants to play) buys a guitar...right?? No guitarist worth a damn keeps his instrument stock, so all guitars are designed to be modifiable. However...if you modify your instrument, your warranty becomes null and void and you must pay to get anything done by the manufacturer after that. (which nobody does.)
Now...
How is this relevant??
Allowing this custom firmware or open source or whatever we decide to call it will open up a world for the homebrew enthusiast and Sony can say "Here...mod the $h!t out of your PsVita...this will void the warranty but if anything goes wrong you can buy another one." They could make a ton of money on the wannabes who have no business modifying anything and the overall gaming community can benefit from those who DO know what they are doing.
I see great things for both sides.
Let the arguments and flame wars begin.