Nixing support is most likely for the last reason, but this too can show the unaware that SOPA is NOT just about "protecting copyright." It's about incurring real financial costs in order to support the whims of a chosen few. Then it can be further explained that the monetary cost is only the beginning, and that it will be abused to silence dissent in ways that make the DMCA look like a jaywalking fine.
Everyone, not just the techies, needs to be made aware of exactly what SOPA and it's evil twin are, and the threat they represent. If you have non-techie friends, explain it to them in terms they will identify with. Going into all the talk about protocols, blocklists, etc, will probably garner the same reaction it got in the House...i.e. "I don't understand this because I'm not a nerd." But if you show them how it will impact their daily lives, they'll get the picture.
It's a pretty grim picture given that congress doesn't listen to the people they supposedly represent. But if enough of those people start voicing their disagreement with it can still be stopped. That's why the word needs to go out to everyone. Forget Linux on the desktop, make 2012 the year SOPA is buried in a deep-dark hole never to be seen again.