Regardless of a person's specific interpretation, most authorities agree that heirlooms, by definition, must be open-pollinated and bred and stabilized using classic breeding practices.
Heirlooms must be open-pollinated. This was by definition. This is what most authorities agree. Heirlooms bred. This was by definition. This is what most authorities agree. Most authorities stabilized using classic breeding practices. This was regardless of a person's specific interpretation.