Guys like Kellerman were approaching retirement. They know what happens to a pension when an individual gets a wild hair up their arse and bucks the system. Same goes for SA Clint Hill. I have trouble accepting anything he says when he continues peddling the narrative that the JFK Limo did NOT STOP at any point on its' journey to Parkland Hospital. CT's and LN's alike KNOW the JFK Limo did STOP at some point before reaching Parkland.
It's not an all-or-nothing situation. The fact that Kellerman denied the limo stop makes his statement that there had to be more than three shots all the more compelling because he was contradicting a kay aspect of the official version.
Kellerman had a vested interest in denying the limo stop, since he was in command of the limo. He should have screamed bloody murder at Greer when Greer started to slow the limo after at least one shot had been fired and heard. If Kellerman had admitted that Greer stopped or markedly slowed the car, he would have had to explain why he, Kellerman, did not immediately order Greer accelerate the split-second he noticed the car was slowing down.
For that matter, Kellerman should have immediately jumped over the back seat and shielded JFK with his body as soon as he heard the first shot--this was his specified duty in the event of gunfire. Special Agent Youngblood did exactly this in LBJ's car as soon as he heard a shot--he vaulted over the back seat, covered LBJ with his own body, and yelled at everyone in the car to get down. Kellerman did none of these things.