i believe this covers it: “Cadaver skin has been harvested for a long time for use as temporary wound coverage. If you try grafting it on someone else, their body ultimately mounts an immune response and rejects it. Still, it can make an effective temporary closure for very large burns. A number of companies turn cadaver skin into commercial products like Alloderm by removing the proteins from it that trigger your immune system. Alloderm (usually processed from the very thick back skin) is a very strong material I increasingly use during breast reconstruction”
So basically, you CAN get a temporary skin graft from dead bodies (even though there will be an immune response) source