Given the extremely limited nature of the site, what protection do you think TLS would offer (against an adversary like the NSA that could trivially correlate your IP address with your email address).
Remember what happened with "Anarchist's cookbook" and recipes for thermite and such that used to be readily available on the net, and relatively uncontroversial. It was just "information" after all. These days it seems knowing how to do some basic chemistry is considered intent to do harm or something.