I can somewhat accept that, but truthfully, if it's a situation like you describe (1st point), I wouldn't even roll dice (well, possibly for "appearance's sake"), but I wouldn't leave a death like that up to chance. As for semantics, yeah, this could be considered such, but having to actually spell out our beliefs helps us sharpen them. Also, what's good for one group of gamers isn't good for another. His players might lynch me were I to DM for them, mine might do the same for him.
Second point I refer you to this >>16000794 post I made. I admit, I don't fully follow rules, but like you said, if the PCs make a dumb choice, I'm going to at the very least harass them for it. Taking someone prisoner in some situations is dumb, other times it's brilliant. Additionally, I don't always consider the encounter ended once the enemy has quit the field. Again, you may call this semantics, but for the most part, I don't think there should be the same level of XP just because the PCs are still standing. Maybe I just require more out of them, but then I always also believed that people rise to expectations and have been only rarely disappointed.
Third point: I admit to being pedantic in this case. Also, I'm much more of a 2e person than any other flavor of DnD, so that might be the source of some of my cynicism.