GSD comes in different types. For the purpose of this point, I'll use those types which include hypoglycemia as one of the symptoms.

Here we have at least one possible underlying condition which could explain a true glucose deficiency. However, unlike what Jaminet calls "glucose deficiency", GSD results in a true glucose deficiency which we call "hypoglycemia". These forms of GSD benefit from dietary glucose supplementation, yet we are not otherwise confused about the source of the disorder, i.e. we don't call them "glucose deficiency disorders".

Accordingly, we have at least one example which shows us that even though Jaminet argues in favor of dietary glucose supplementation for treatment of some disorder he calls "glucose deficiency", this disorder is not in fact a disorder of glucose deficiency, but some other as-of-yet unknown disorder.

We often use an analogy: Nobody suffers from statin deficiency.