For what it's worth, I think valid points have been made from both sides of the argument.
Personally, I think it would be ridiculous for someone to neg a seller for updating a listing that they had placed a snipe for and won simply because they hadn't re-checked the listing at any stage and taken note of said updates. Buyers should be aware that this can happen, just like many other circumstances and potential pitfalls that can occur and not only take measures to avoid them, but take responsibility if they could but choose not to.
That being said, just because I think that kind of behaviour would be unwarranted, doesn't mean it can't happen. Sellers have been negged for less - I was negged because my description was accurate!
So, as a seller you also have a choice as to how you deal with the potential for things like that to occur. Rules and policies aside, in simple terms, when you create a listing you can do everything feasible to cater for the lowest common demoninator (for lack of a better way of putting it) and avoid things that can result in conflict with a buyer (whether reasonable / fair or not), or choose to risk taking a few hits from surprised / upset / disappointed people and possibly-maybe educate them / alter their future buying behaviour.
One method will make things ultimately easier for a seller, the other method may or may not make things easier for all sellers.
