BBC executives had given the go-ahead for Clarkson, 55, to guest-host the satirical news quiz next month despite dropping him from Top Gear after he punched producer Oisin Tymon.
But the usually-abrasive star changed his mind after recalling the merciless mickey-taking that former host Angus Deayton, now 59, got from Merton, 57, and Hislop, 54, in 2002 over cocaine and prostitute allegations.
“Angus got slaughtered and Clarkson suddenly realised he would be in the line of fire himself.
"He would be in a no-win situation.”
“He knew he couldn’t expect an easy ride from Ian and Paul and would be held up to ridicule. He maybe felt it wasn’t worth the hassle.
“In the cold light of day he decided it would be a wise move to pull out of the show and wait until the dust has settled later in the year before going onto the show.
“His decision came as quite a shock to BBC bosses - because they’d only just given the go ahead for him to appear and had gone public with it.”
Clarkson was suspended by the BBC for allegedly attacking Tymon at a Yorkshire hotel on 4 March in a row over cold food.
Director-general Tony Hall made the decision not to renew his contract after ruling “a line has been crossed” and “there cannot be one rule for one and one rule for another”.
But, a BBC spokesman confirmed that he isn’t banned from appearing on the BBC and his HIGNFY appearance had been cleared at the highest level.
Jimmy Mulville, managing director of Have I Got News For You producer Hat Trick, previously spoke of how he hoped Clarkson would continue to be able to guest present the show as they “always have a field day” with him.