Police have yet to make any arrests over that incident, and say their investigation remains open.
"The connection between the two incidents is extremely similar," said Detective Inspector Jason Weinstein. "At the moment we are looking for anyone from a straight-out arsonist to someone who might bear a grudge against the operators."
However, the manager of the Kings Cross franchise, Damon Singh, dismissed speculation about a turf war, noting that his was the only pizza delivery outlet in the district. He told the Daily Telegraph that the latest fire was disastrous timing, but said league fans did not go without pizzas during the match between the NSW Blues and Queensland Maroons. He said they had the use of bikes from other stores.
There was speculation that residents angry about noise made by the delivery scooters could be behind the attacks. "People have been coming in with a lot of conspiracy theories," said Paul Ryder, owner of a nearby cafe.
"There's a lot of talk from the locals that the pizza guys rev up the bikes when they are putting them away ... apparently residents have made noise complaints but it keeps on happening."
Knight, 29, who was visiting the United States at the time of the attack, is the company's largest franchisee in Australia, he was awarded a "Gold Franny" by the International Franchise Association in March.
Domino's said it took the two incidents very seriously and was co-operating with the police investigation. "Thankfully the scooters were unoccupied at the time and no one was injured during the fire."