MI5 Persecution: How Could It Be True?

If you have the patience to read these articles you will be struck by how
apparently fantastic the claims being put forward are. You may ask
yourself why such seemingly nonsensical assertions are made. This matter
has been discussed on the Internets UK-local newsgroups for three years
now, and the denizens of the uk.misc newsgroup (the so-called
"miscreants") have come up with a number of theories to explain these
posts; it has been variously suggested that they are a troll (an
artificial creation for the amusement of its author), that they are made
by MI5 themselves with the purpose of discrediting other conspiracy
theories, and that the poster is mentally ill and the articles are
symptomatic of the illness (the view held by most miscreants).

Are these claims the product of mental illness, or is that just a cover?