He doesn't; Litwin is all about Garrison bashing.
Otherwise just a run of the mill LN nut job WC fanboy.
How that would default to some kind of leadership role makes little sense to me.
Not true at all. In his first book he has one chapter (out of seven) devoted to Garrison and the rest of it to discussing other conspiracists and conspiracy theories and how his views on the assassination changed over time. Although he does mention Garrison in other chapters.
Furthermore, exposing Garrison's serial abuses of power, his incessant lies and falsehoods (although he probably believed many of them) is not "bashing." It's exposing Garrison for what he was: a ruthless, paranoid who ruined numerous people's lives.
This is from the table of contents of his book "I was a Teenage Conspiracy Freak."