1. if you're going to link to something, please use the add a link button. it's right above the box you type in and makes it much more likely that people will actually look at what you are referring to.
2. fruit rotting in your gut seems a bit off to me. your body is designed to take in and process foods, getting the maximum value possible out of them. if it has broken down to the point where fruit is rotting in there, eating fruit first is not going to fix that kind of breakdown, you're probably going to need to go to the hospital. i mean, your digestive tract is basically a bunch of long tubing with an occasional balloon for mixing. yes, some things will get digested a little faster or slower depending on what else is in there. but the point of mixing foods together is so that you don't get that sugar spike and aren't hungry an hour later.
as far as not eating fruit before bed because of a sugar spike keeping you up, well some people do have a problem digesting and sleeping at the same time. but if you aren't one of those people, i don't really see the point.
i think there is some truth base in there somewhere, and particularly for someone having upset problems, but you can't apply a specific condition need to the whole population and make a generalization based on that. it just feels like if you only get 1/3 the value of the apple if you have it with peanut butter, someone in the scientific community would have figured that out by now and there would be asterisks all over the food pyramid/plate/equivalent saying to make sure to eat fruits separately. whereas if it's it's really true you get reduced yield, it's in the same way that cold water burns more calories or spicy food burns more calories, true, but such a minimal change [a thousanth of a percent say] that either way still gets you nearly the same results.
-google first. ask questions later.