Irrelevent. If Sony allows unsigned code to run, they can't stop any arbitrary Linux app from being ported. Even if Sony creates a program for people to publish signed apps for a small fee (as opposed to full fledged games), it would be succeptable to homebrew. There's simply no way Sony can vet all code.
Now, there have been rumors of Sony opening up the PS3 platform, and if this is true in anyw ay, even cheap publishing, it will blow the doors off the platform. Even an innocuous program like a Tetris clone, if Sony signs and publishes it, could be have a purposeful bug inserted to allow it to be used as a bootloader for unsigned homebrew code.
In short, if Sony takes any course other than keeping the platform closed to only 1st and 3rd party developers, they are effectively opening it up.
As for homebrew being small but vocal, it's only small because the only way to play homebrew is through technically arcane procedures or worse, getting your hardware modified. That would all change if installation is as simple as point and click and download.