I think it should be "one less home" or even "one fewer home". We all should have figured out singular and plural nouns in grade school.
If the itme can be counted the adjective is fewer. For example, I own fewer homes then John, and they are also less luxurious.
“Fewer” is preferred when refering to things which only occur in discrete units like homes, wives or loaves of bread. Less is preferred when refering to things measured continuously like gallons of ketchup, tons of sand or cubic feet of hot air expended by Joe Biden.
“One fewer than John Kerry” would have been preferrable, but the grammar police usually won’t cite you for using “less” in this case.