You’re right, of course. But, IMNSHO, they are wrong.
You pays your money and you takes your choice.
Communicating with demons masquerading as the spirits of the dead is something that I would never do. Although, for a Christian, I have a truly disturbing, to me, fascination with the occult.
This isn’t communicating with demons. These people (live souls as you say) are on their way to heaven.