Is it correct that Port Elgin is measuring sunflower plants with the tap root included? And are other weigh-offs doing the same? The correct and official way to measure sunflowers (and tall corn) is without all roots. In the case of sunflowers from the base of the stalk to half-way the sunflower face. In the case of corn, from the base of the stalk to the top of the tassle, or by lack to tassle to the fold in the top leaf when standing up straight.
If PE is doing so, that would disqualify all contenders, including those claiming records.