Yes, it’s possible to create a membership to this diary. It’s possible to create a member profile, too. I discovered that I’d left those options open when I started getting e-mail notifications of people registering.
At this point, registration serves no purpose — I haven’t enabled comments for anyone, and haven’t enabled posting. The diary has no secret features — what you see without registration is all there is. And I’ll never open up the diary to enable posting by others, for what it’s worth; however, I cannot say that I’ll never enable comments, — I’ve REMmed them out in the template and don’t intend to bring them back, but some compelling reason might occur to me in the future. If you think you’d like to comment on posts if that option were ever offered, go ahead and register.