We have always accepted both art and fic that feature Severus Snape and Harry Potter, whether or not they actually have sex together. Josan's fic is a wonderful study of the two truly communicating for the first time, and of Snape's efforts to save Harry once more before he dies. In the end, Snape is unable to touch Harry as he clearly (and Harry) wants, so he uses someone else's hands/body to do it.
I considered warning for Harry/OMC, but I also thought it may 'spoil' it. I believe Harry speaks of other men he's been with during the past, his one-offs, as well, and we don't warn for that generally, either.
I will consider putting it in, once I discuss it with the author.