Both DS9 (2e) and DD8 (gifted, not 2e) have aspects of what you describe in your son. There are times when DS seems to be "dense" and answers questions as he hears them literally. But other times doesn't. I think it depends how engaged he is in what he's doing, but I haven't found a pattern yet.
Both my kids will give "non-standard" answers to simple questions, or just be unable to answer them. They are used to thinking big, so if someone asks them a simple question, they often overthink it. How are a bush and tree similar: do you mean biologically, or as a habitat for animals, or growth patterns, or where they're found, or how I like them, or if they're both in Minecraft, or ....
As for peeing one's pants, DD8 still has accidents (although they are becoming increasingly rare, thank goodness!) She gets very involved in her work, and doesn't want to stop for something as trivial as peeing. I also suspect she doesn't feel the sensation of having to pee until it is quite strong (and sometimes too late). I haven't figured out how to help her with this, other than to remind her to use the bathroom frequently throughout the day.
