To me, the don't JADE guideline is for situations where the individual is likely to push back. It would not have occurred to me that this was one of those times. And if I had not elaborated to the HC, I could totally see myself having a conversation with a friend (ie. the bride's sister) about this in more detail as I do with many of my friends. I think it's one of those situations where in hindsight we easily see the "error", but in the moment, I am not completely convinced that it is so clear.
That said, I think the real blunder was on the HC and/or bride's sister/friend for organizing this without consulting the LW. I don't think that they meant harm, but I do think that they overstepped.
I also think that MM's response was not only off, but very condescending and borderline rude. Even if the LW had done something wrong (and I am not totally convinced that she did), I think the wording was so snotty. I prefer to take my advice from kinder and more polite people (oh look... an entire forum!!!)
I agree, that if I was the LW, I would decline the offer and this is certainly NOT a moment to JADE. "That was thoughtful, but that is not going to work for me." Someone else also mention that it would probably be a relief for the driver, as he would probably prefer to make the trip with his girlfriend.