After casually meeting with Kangaroos chief executive Jen Watt and football boss Todd Viney this week, Simpson won't be putting his hand up for the coaching position.
Simpson, who left the Eagles mid-2024, has often been linked to the North job after being a champion of the club across 306 games.
"I never crossed the line (to apply) because once you cross the line there's no going back, once you're in you're all in," Simpson told SEN on Thursday.
"That was the hesitancy of it all.
"There is my history with the club, knowing some people there, and having that thought that would be cool.
"But after starting that process I realised that in the end, it probably didn't suit me as well as I thought it did, and then the decision was made that didn't have to go the all-in."
After headhunting Clarkson - a four-time premiership legend at Hawthorn - in 2022, North appear likely to choose a first-time coach from the crop of assistants around the AFL.
John Longmire, who like Simpson is a former Kangaroos hero and a premiership coach, is yet to make a call if he wants the job.
Current AFL assistant coaches Jaymie Graham (Fremantle), Daniel Pratt (Western Bulldogs), Corey Enright (St Kilda), James Kelly (Geelong) and Daniel Giansiracusa (Hawthorn) will be heavily considered by North if they choose to apply.
"There's an undercurrent across the competition at the moment that the new (coach) is the new fashion," Simpson said.
"Which is absolutely fine.
"I was on the Carlton coaching panel a month ago, and I critiqued these young coaches that potentially you go against.
"I'm not that comfortable going through exactly the same process."
Clarkson was sacked earlier in September with a year to go on his contract after winning just 20 of 82 games as North coach.
During a blunt press conference following the axing, Kangaroos hierarchy declared they wanted a "modern coach" and strongly suggested Clarkson had lost the players.
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