In a surprise move, the French team produced Lomu's two boys at a function in London on Monday featuring presentations from the rival bidders for the tournament.
The French rugby federation flew seven-year-old Dhyreille and Brayley, eight, over from New Zealand with their mother Nadene for the event.
TVNZ described the pair sitting "awkwardly" on former France winger Sebastien Chabal's knee as he explained why they were backing the bid.
"Dhyreille was born in Marseille when he (Jonah) came to play (three games for Marseille in 2010)," Chabal said.
"As he (Dhyreille) told us earlier, quite simply he is known at school as the 'Frenchie' and Jonah Lomu loved France."
While the links may appear tenuous, Fairfax New Zealand rugby writer Tony Smith conceded Lomu, the sport's first global superstar who died after years of battling kidney disease, was revered in France and many other parts of the rugby world.
But he questioned the ethics of France using two primary school-age boys, who lost their father less than two years ago, as the face of their bid.
"It might be different if they were in their mid-teens, but Brayley was six and Dhyreille five when their beloved dad died," he wrote.
Smith said their involvement "run(s) the risk of being accused of a word common to the English and French languages: exploitation".
He suggested the numerous ex-All Blacks currently plying their trade in France, including the legendary Dan Carter, would have been better bid ambassadors.
Radio Sport NZ host Martin Devlin had similar concerns.
"If you have children and they've gone through the ages of seven and eight, you'll know what I'm talking about, those kids don't know what they're doing there," he said.
He added: "If you've got a seven and eight-year-old you're exploiting them is what you're doing."
Rugby commentator Andrew McKenna, from Britain's Talksport, described the French presentation as "bizarre".
"You've got Sebastien Chabal and Jonah Lomu's kids, everyone's like 'What the hell's going off here?" he told Radio Sport.
"They explained it and said one of them was born in Marseille when Jonah was playing, but (it) all felt a little bit odd."
The children's involvement also ruffled feathers among commentators in Ireland, which along with South Africa is also bidding for the 2023 tournament.
Irish sports site ball.ie labelled the stunt "emotionally suspect", while Irish Independent columnist Jack O'Toole said some would find it disturbing.
"When you pluck two kids out of a country on the other side of the world and drop them into the middle of your facade to accentuate their link to their deceased father, it's just desperately insensitive and depressingly sad," he wrote.