You know, some people like arguing about Star Trek physics others like arguing about ancient pronounciation. Who are you to judge?

Anyway, Back on topic, let me provide the thoretical outlines of the theory of the BGD pronoungiation: phonetic stucture of a language is called like this, because there actually exists structure, that is method to madness. Ancient Greek has no voiceless fricatives: Φ,Χ,Θ were pronounced ph, kh, th that is the first like "p" in "pot" the second like "k" in "kit" and the third like "t" in "tip". This we know because even the letters Φ,Χ,Θ do not exist in old inscriptions but you find ΠΗ, ΚΗ, and ΤΗ in their place, that is stops with the sign of aspiration (H). Corresponding to this class of consonants there are their non aspirated variants Π,Κ,Τ. Now, there really isn't much sense in a phonetic system of this sort that those varieties of consonants coexist with a class of voiced fricatives, i.e. β,δ,γ (moddern pr.), because those would not correspond to any other class of consonants. If they are stops, they do correspont to Π,Τ,Κ as their voiced variants. The advantage of such a system is that it is homogeneous, as classes of consonants naturally correspond as variants of others. The existence of β,δ,γ in the consonantal system of Greek would have been a rather major aberration.