Example. The Green and White Mountains are the hardest part. I'd say at least of those who have hiked the trail would give the nod to the Mahoosucs of Maine. Someone who has only read books would parrot the Whites and I don't know where he got the idea of Vermont.
More telling - he says no one has broken the record northbound. Completely false. Most of the earlier records were northbound.
He obviously has some skill and ability, but that is not enough to set the supported record. He'll need endurance of a scale far beyond that of a any endurance race. He'll need luck with weather, and an experienced support crew, which he does not have, at least in regard to the AT. At this point, it sounds like he has less experience than a typical thru-hiker planning a six month walk.
Like many have said already, he should walk the trail first and really learn the trail's idiosyncrasies. Then he should consider whether he wants to shoot for a record.