I’m speaking from experince
The mesh tent that I use has a fly that goes down to within a couple inches of the ground. Sure, when the wind blows, the breeze going through the tent is much slower than the wind outside, but the breeze is very apparent and the rate of air exchange is too fast for the air moving through the tent to gain heat before it's gone out the other side.
I'm not speaking in speculative context here, and it stands up to logic too. During a light breeze it may be possible to get slight heating inside, especially during a sunny day. But in my other post I was talking about during a brisk wind and assuming a night-time situation, and in that case, forget about it. There won't be enough heating to notice. But you'll sure notice the cold breeze.
Oh, and don't attempt to confuse the issue by introducing the effects of blocking most of the wind and reducing the rate of heat loss from your body. I didn't and wouldn't say that blocking the wind with the fly doesn't help your body stay warmer than it would if directly exposed to the wind. What I am saying is that the actual temperature of the air inside your tent won't be any warmer than that of the air outside if it's gone from your tent a couple of seconds after it enters.