GMM, posters like you are a pain. You ask a fair question and you get good answers from professionals. But that's not good enough and you need to ask what is basically the same question again! Then when posters become a tad cynical with you (quite deservedly) your "innocent little me" defences go up:
I had no intention of starting an argument, this was just an innocent enquiry
At the end of the day, my friend, only the Captain will know why he made that decision. He (and quite possibly UPS Ops) no doubt had multiple factors to consider (as already explained to you) and the final outcome was to divert to LHR. He, unlike you, is a professional and he excersised his professionalism by making a decision based on all the information that was at his disposal at the time. So be it.