Do you really think the average outraged teenager/citizen is going to have the time, resources, or know-how to assemble Paranoid Linux, XNet with Tor, gnupg, WiFi sniffers, security tools, etc.? Why would anyone in their right mind do that when a public, mass outlet has emerged for similar expression? Further you gain credibility by having multiple, collaborated sources, far more than some literally untraceable, anonymous internet source. One blog entry isn't noticeable or likely to get attention, 10,000 agreeing Twits definitely is.
Pragmatics aside I can't believe you're encouraging "revolutionaries" to comply with government suppression. Doesn't that defeat the point of an uprising? Maybe all the Iranians should just listen to the police, go back inside peacefully, stop telling the world what's going on and accept the latest government announcement. Maybe while they listen they can invite over one of their 100s of Linux-qualified friends to help them set up an anonymous network connection!
Twitter isn't going to save the world but it has a way better chance than anonymous Linux browsing.