A very good question. Joe Ball wanted Brennan out and Belin asked: if you were sitting there then where are your legs dangling over the ledge?
He was not sitting where he said he was. You can see that in the Z film.
As I showed with Thornley, and Tim does here, the WR was a conscious deception. These guys knew it was a put up job and they went along with it .
https://kennedysandking.com/john-f-kennedy-articles/did-even-the-warren-commission-believe-howard-brennan
You'd think so, right? Would you say he saw anything significant based on this other than a description of Robert Webster? The man they catch was 5'9" 135lbs....
Did this a number of years ago.... pretty sure a moment in time is NOT indicative of line of sight throughout... but I did find it interesting where everyone was facing and concentrating on... especially hard hat man by the lamp post who never seems to turn to his right to follow the motorcade... he only looks up Elm...