I think the majority of the audience for this sort of course will have a blog or a microblog... even if it has lain inactive for a while. Those that don't could create a user subpage that was their blog if they don't want to join one of the existing services. It seems far more inclusive to aggregate content from existing social media than setting up another instance. Prominent services (and WikiEducator pages) can be harvested by RSS and/or API calls.
Those that do want to create a new microblogging account at Status net can use an existing OpenID provider for it (and for their WikiEducator authentication)... so while there are two "accounts" there is only one authentication.