I had to make the same decision not too long ago, and decided friends was the way to go. Different circumstances, but same idea. I didn't want to be her baggage.

A lot depends on activity level of your friend. If he is ougoing, likes to go clubbing, etc etc he may find himself doing things alone a lot. The woman I kept things on a friendship level with said she loved me but she is also very active and high functioning. My gut told me that I would be a drag on her, or keeping up with her would be an undue stress on me, until/unless I got at least somewhat better. She is now a good friend and we both think the right decision was made. She's seeing someone else romantically who I think is more appropriate than I am right now in my current state and I am happy for her. And I don't have a constellation of expectations over my head. I can set my own pace for myself. And I will have my own intimate relationship when the time is right.

Right now I would rather be surrounded by a lot of people as supportive friends than involved in an intimate relationship that tends to attract a more exclusive and intense focus. Better to be open to and love a lot of people for me, without the fog of intimacy. An intimate relationship is a lot of work. Sometimes it can be just what the doctor ordered, but just as often it can turn into a huge stressor; a claustrophobic rather than an open thing.

My 2 cents. Sounds like your gut is telling you the same thing mine was, although the specifics no doubt differ.