Greetings David,
I am not too familiar with the exact specifics of “topping” post oak (Quercus stellata), other than the obvious fact: completely removing the photosynthetic engine (crown) of a tree is bad, any way you look at it! No crown = no leaves; no leaves = no photosynthesis; no photosynthesis = no new carbohydrate production for tree maintenance (respiration), growth, and reserves for next year. Yes, you will get probably get some sprouts and new foliage, but the damage is already done. Oak wilt is also a problem when topping oak trees, as it creates a lot of exposed surface area for insect vectors.
Post oak is probably no different that any other white oak species (Leucobalanus). Either way, the result is usually bad! Death sentence, possibly. Topping any tree, as you well know, is not advisable.
That is about all I can tell you from my knowledge and experience.
Jay