My doctoral advisor has been on medical leave for several months now. As such, he has been extremely hard to maintain contact with. He lives in a different part of the country and checks email only about one or two times a week. This usually has not been a huge issue because I know what I need to do for my dissertation and have been doing it.
In keeping with a discussion that he and I had about three months ago (which was a continuation of several prior discussions on the same topic), I have agreed to terms for a full-time job starting in six weeks. Part of the contingencies of the job require that I actually have successfully defended my dissertation.
Today, he sent me a terse email to inform me that he needs to take care of some of his medical issues, and then he will contact me and we can try to "finish" the dissertation. This is a deviation from previous agreements he and I had. Outside of any last edits he would want to add though, the chapters for the dissertation have been done for some time now. I am just biding my time, waiting for him to give the final go ahead to submit the dissertation to the committee. I have conveyed these thoughts in email to him, but he has ignored these emails.
My question is this: Has anyone ever declared their advisor "medically unavailable" just weeks before trying to defend their dissertation? I am essentially faced with the decision of delaying the start date for my job (while still paying rent all the while) and keeping in the good graces of my absent advisor, or, alternatively, going to my department and seeking to have my advisor declared medically unavailable. Because he would possibly still need to sign off on my defense paperwork, I am worried that my advisor could try something to still block me by refusing to consent to signing the paperwork.
ADDED
I will add here a few details about why my advisor is on medical leave. He is not sick or dying. He had a routine procedure done on his knee about five or so months ago. Millions of people have undergone this procedure and return to work within a week. This is not a case of a poor old man who is terminally ill. I do not think it is unreasonable to ask a guy who had routine knee surgery to respond to emails five months after the surgery.