I like the concept of this plan, of building in some democratic community building within the consideration of democratic principles.
Your lesson plan is marked up with highlighting which I know is based on applying UDL principles to it. It is a little distracting to have these highlighted sections, but since you do I’d like to address some of the areas you have highlighted as barriers. I believe you are concerned with the textual nature of both the input and performance tasks. Perhaps you could add an audio version of The Universal Declaration of Human Rights and have some students use vlogs rather than blogs. Using something like VoiceThread might work well for this as well.
A suggestion I have for taking this to the next step and using the online community for an actual task is to ask the students to come up, as a group analogous to a legislative body, with their own declaration on human rights or a statement on some particular human rights issue that they may encounter.
It might be helpful to have a link to Edmodo and other similar sites that could accommodate a lesson like this.