I remind you that academic freedom is a limited protection, and applies only to your research and classroom teaching, and, in the case of the latter, to discussion of materials relevant to the course subject.
Otherwise, faculty can be (and have been) punished for written and oral communication that is disruptive or uncivil.
This strikes me as a new, crucial frontier for defining academic freedom. We still need protection for saying possibly-unpopular (but subject-relevant and professionally supportable) things in the classroom and in our research, but, in the present climate, we also really, really need the freedom to discuss and, when appropriate, criticize institutional structures (present and proposed) and their effects on our work. I'm glad to see Jonathan Rees raising this issue on the AAUP's Academe Blog (where I first saw the letter), and I very much hope the AAUP will pay due attention not only to the threat posed to tenure by department cuts, but also to a kind of academic freedom that needs to be protected for the sake of all faculty, tenure-track or not.