I've never heard of that happening either. Domestic rabbits generally won't harass sick or old rabbits either. If anything, ours seem to know their friends are sick and spend extra time cuddling and grooming them.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry