I don't know why the defence haven't been making a big deal about the gastric transit time, because it is an absolute slam-dunk win for them. My only conclusion is that they have to a large extent fallen for the "unreliable" meme without really understanding the details of the issue. In particular that it isn't about gastric emptying. Also, that there are so many aspects to the case and in particular the prosecution kept changing its ground so they became snarled up in other matters.
In the other case I have been looking at, I discovered that the defence had had in their possession all along the evidence that conclusively proved their client was innocent, and they hadn't realised it. Again, it is really obvious, but it was something they simply had not considered in the middle of looking at a lot of other, less obvious matters. And interestingly, the hardest person to convince was the defence researcher who had given me the evidence. He simply couldn't get his brain round a different way of looking at the case, or the idea that he had missed something that someone else new to the case had spotted.
So really, the "why didn't the defence make a big deal of this point" isn't much of an argument. Lawyers failing to grasp something really important is actually distressingly commonplace.
Rolfe.