You might, actually. Of course you do once the "real digestion begins", but technically speaking you might have a cephalic response to it as well. First, because cephalic response is, at least in part, acquired. Second, because there is an enzyme in your saliva, called amylase, basically the same one your pancreas has, albeit it won't have enough time to do much. Regardless, it's said that if you chew and don't swallow things like bread, or starches in general, the amylase should have enough time for you to taste sweet. I can't say I've ever experienced it myself, but it's something you'll find written on every book about digestion. Technicalities anyway.
The main point is, the taste is just a part of the cephalic response. Chewing is actually also, technically, a part of it. Even thinking about food triggers a well-known cephalic response, "mouth watering" as it's known. Hypersalivation expecting to need saliva to handle the bolus is, in its principle, similar to expecting the need for insulin to handle the sugar.
Unfortunately, it can be released in both scenarios. To what degree, that's the question.
Or we would be smart creatures for preparing for the upcoming release of energy into the bloodstream, since hyperglycemia is also potentially dangerous. From an evolutionary standpoint it would make sense that you would associate taste with incoming calories, because, well, in nature that'd always be the case. It's like bracing for an impact, which your body has no reason to suspect won't be coming. Perhaps it makes more sense for the stomach to produce acids during the cephalic phase, rather than insulin being released, but even then one might argue that it's a waste of energy to preemptively prepare to digest food one is yet to ingest.
I do understand your point, it would be more efficient if our body waited until the last moment before sugar went into the bloodstream before releasing any insulin at all. For that matter, however, our body could also be smart enough to understand that once you are 20 Kg overweight it's time to signal a stop in appetite, or that if you keep struggling with that 405 bench press it's probably time to signal an increase in muscle synthesis. Alas, our bodies are not always efficient, and that's why we have fat fucks in the street and plateaus in the gym.
I'm not familiar with Layne Norton's content, but I did watch the latter's videos on the topic. I don't recall him ever addressing this particular concern.
While it would be nice to believe them, we are talking about high-level athletes. And, at least in Greg's case, people that do so much cardio that the impact of a few sodas would be counteracted for sure. On a smaller scale, for the average Joe like me, the impact might be bigger though.
That's kinda why I was asking for anecdotal reports, since science has (to the best of my knowledge) failed to give a definitive answer. It's really easy to fall for the confirmation bias though, and believe only the anecdotes that support what you want the answer to be.
I do have to wonder, though, with what people pay to buy insulin and IGF-1 for doping...if diet sodas really had a significant impact on insulin response, then maybe they should just take a can of coke at each meal during their bulks, and save the money and risk associated with doping with insulin. It would have to go both ways, after all, and it'd have to be as bad for cutting as it'd be beneficial for bulking.