But Palmer took him at his word and stopped the car before leaping on his stepdaughter's partner and trying to gouge out his eyes.
All three - the two men and the cat - ended up outside the car.
As the cat fled into the bushes, Mr Temperton grabbed his favourite Pink Floyd Dark Side of the Moon coffee cup for protection.
Palmer's lawyer, Doug Taffs, accused Mr Temperton of throwing the cat out of the car when it stopped.
Mr Temperton said the cat had exited by itself.
"Do you honestly think I care about the cat? I care about my girlfriend and my son," he said.
He later amended his priorities to include his Pink Floyd cup.
After the dust had settled, Palmer told the couple they could no longer live at his house.
The couple drove home and started packing their car, leaving Palmer to find the cat.
But as they were about to leave, Palmer returned and smashed their car window with a set of bicycle handlebars. Palmer said Mr Temperton had tried to run him over.
Judge David Saunders told the court that whatever had happened, the adults' behaviour did them no credit.
"It must have been extremely upsetting for a child to see adults losing control like this," he said.
He convicted Palmer and sentenced him to 150 hours' community work.