JC--
I think the US right-wing largely went down the LN theory-rabbit-hole with the release of the WC report in 1964. In the right-wing of that era, there was a near-reflexive reverence for authority, and the WC represented authority.
The WC in 1964 struck exactly the tone the right-wing wanted to hear: a soured Marxist leftie loser lone-nut perped the horrid JFKA, but not on instructions from Havana of Moscow. No nuke war needed.
The modern-day right-wing is a different animal, and sometimes reflexively rejects authority, and so you get a different reaction to official JFKA theorizing, with just as much justification.
The agenda write the narrative.
Keep in mind you have former CIA Director James Woolsey's book, Operation Dragon: Inside the Kremlin's Secret War on America, presenting the view that LHO was a Russian operative. Woolsey was a CIA director, and a right-winger. Woolsey is a deeply knowledgable fellow when it comes to spy work. You and I are admitted hobbyists next to Woolsey.
So I defer to Woolsey or you?
As for LHO being in the TSBD, that was luck or circumstance, as was the decision to have the JFK limo make a hairpin turn in front of the TSBD. You are making the obviously baseless assumption that a JFKA CT required the knowing placement of LHO in the TSBD in preparation for the motorcade. Rather, LHO was there by chance, and G2 or KGB took advantage of that situation.
Keep in mind, at anytime in the 1960s, the KGB and G2 had hundreds of assets, plants, double-agents, agents, and informants in the US. It is legend how thoroughly Castro had infiltrated the Cuban exile community.
LHO appears to have been one of those G2-KGB assets, and he had a job in the TSBD. So he was utilized.