Hmm. If you had stated that information in the original post about that guy, we wouldn't have assumed that you hadn't thought of doing that stuff. (Again, if we were telling it, we'd include every possible detail so as to avoid that sort of thing. I realize that Te users would assume that would be surmised and often find the inclusion of it annoyingly extraneous. Interesting to note the differences).
Your comparison about the red apple thing though: What if the person had been told by his Mom that he would get a yellow apple? What if he didn't think you would have had reason to see his lunch and were only trying to strengthen your point by saying you had? What if he was sure that his lunch was in a secure place and therefore didn't factor in the possibility of a nefarious apple swapper? What if last he had known, they only had yellow apples available at his house and he didn't realize his Mom had gone shopping. To me, these would be the relevant details that would need to be addressed, or at the very least, the reason why you are sure that the apple is red (how did you get a chance to see it?). Unless of course I already trusted in your competence or you had a history that had always been accurate. Then I wouldn't question you anymore.