I think some measure of common sense should be brought into the equation with the whole "Heritage" label. Forget ALBC, heck, forget the APA. The APA does not recognize every old, naturally reproducing, slow maturing breed out there, I'm sure.
What is the SPIRIT of the Heritage monicker? To preserve valuable biodiversity of old strains of poultry, in this case? Is this limited to breeds that held utilitarian function? Where do ornamental and bantam breeds come into play?
To me, any breed with a rich history that was not developed with the benefit of modern industrial agricultural practices is a Heritage Breed. What that rules out is our modern production strains and some "fancy pants" breeds.
Really, from that stand-point, it might be easier to state which breeds are NOT heritage breeds. Isa Browns, Cornish X, Production Reds....? None of those are APA, but are the APA breeds that we can definitively say are NOT heritage breeds? Even the Ameraucana and the Aracauna have a rich history through the Quechua birds someone just posted about the other day.
For the most part, I think this gets down to preserving specific strains and styles of these breeds, not the breeds themselves (Unless you wanted to debate whether or not hatchery stock BR are actually BR at all). It gets down to reinvigorating interest in exhibiting poultry. It gets down to getting back to the point where you have a well-rounded animal that behaves as it should and looks good doing it.
And I think it's awesome, no matter what you call it. I wish there was a "Heritage movement" in the American Kennel Club!