Fuck this chick. Fuck her so much! While it may not technically qualify as graverobbing, it is desecration of burial rights, and that's just a shitty thing to do.
Secondly, it and it's "purpose" violates the most cardinal rule of witchcraft; harm none. Any spell cast with the intent of harming another person (as curses are wont to do) comes with a three-times rebound upon the caster, according to any reputable source on modern Paganism and witchcraft. Hell, our religious symbol is the pentacle; the five points representing earth, air, fire, water and spirit bound together in a circle of perfect, eternal balance.
There are lots of primal religions that work with darker energies and don't subscribe to the idea of karma. Voodoo, for example. A few Indian/Hindu/African religions. But not Witchcraft. Witchcraft, Wicca specifically, operates within very clearly-defined boundaries of intent and conduct.
If she weren't a fucking stupid child, she'd probably know that. But since she clearly has never done any research into Witchcraft (or, likely any other arcane religion) she's likely a fetishist playing make-believe with candles and human remains and trying to hide behind her age and the flimsy excuse of "religious freedoms" to justify being an incredibly shitty person.