The details he provides about proof of employment and wrong-doing by Chrysler when asked to confirm it are very clear. If those are real, we can't tell - this looks like something a good journalist would be able to uncover, and maybe help achieving some kind of closure.
There are certainly aspects of his writing that might be suggestive (the graphorrhea and rambling over minor details, irrational paranoia, etc.) of certain mental illnesses. Since paranoid schizophrenia was mentioned by the parent comment, take that for example: it's not something that comes about because of a single situation later on in life. There are clear, measurable physical symptoms in that instance such as a significant and measurable difference in grey matter. That doesn't happen because of any episode you've experienced.
What _is_ clear is he can barely write, he records videos of himself outdoors that are barely audible, and even if he won this strange case, he's clearly not employable now. More than likely his mental illness started after he became an engineer and quickly progressed.