IMHO...
Over the 42 years I have been in business, I have had a few crackpots "disturb" the otherwise calm atmosphere I try to create around me and those I respect.
I have a Law Firm that I use. My lawyers have taught me to ignore these people and they will go away... and all but one has done exactly that.
These crackpots want an audience. They want you to think "and treat" them like they are important.
The best thing to do is IGNORE them.
I have our webmaster put a block on their email address so our server bounces their emails back to them as if we don't exist any longer. That usually stops their rantings and ravings.
Don't ever answer them.
Don't try to escalate their idiocracy by trying to find them.
Do ignore them.
Do anything to block their communications to you.
If they have a legal issue, you will hear about it from a legit person of the law. Otherwise...
Enjoy life! Ignore those who want to, but have no right to disturb you.