Perhaps "They are more interested in concocting theories concerning his life than understanding who he was" will work. "Man himself" is a bit redundant.
As an English teacher, I would suggest using the word "speculate" unless the person you are referring to has multiple, documented theories concerning his or her lifetime.
I can see why you aced the English sections. I'm a high school English teacher, and I rarely see posts anywhere near that length without major grammatical or spelling mistakes.
Shawnita used to get her pills from some other street pharmacist and after switching to The Psi Discount plan she now only has to swallow two things a day!