At my Regular Place of Work we call these people "High Maintenance Customers", and it took us about half a decade to realize they were not worth keeping.
When someone fits the HMC profile, we detail the situation to them. We give them one chance, and then we ban them permanently. Do not pass Go. Do not bug our customer service base or harrass our product managers. k thx bye.
As for the LOTR Fan from Hell....she sounds mentally ill, and very likely is. She needs help, and maybe the shock of being thrown out of a con would be the jolt in the ass she needs to get her life in order, but then again -- she'll probably just find another outlet for her brand of personality disorder.