I don't think symapthy is sexual in nature, I feel sympathy for a squirrel who can't find it's nuts, do I feel some kind of weird sexual attraction? or the sympathy I feel for the child abused, does not mean I have peadophilic tendancies.
Ergo having sympathy for the dead, is not sexual in nature. When we call a man a peadophile we do not say he did it out of sympathy for the child, so how can you see those who feel sympathy for the dead as being necrophiliacs?
It's not even feeling sorry for the dead, it's feeling sorry for the end of their life, the end to their existance, especially if they failed to achieve or spent a life in misery. It's sympathy to the loved ones left behind, or empathy.
People who mourn the dead, don't usually want to screw them, and if they do then that's when we get the white coat men in.