The reality is more complicated. I put a comment a couple of days ago: https://news.ycombinator.com/item?id=45367307

I'm not really sure how your comment would disprove the story. It seems that it's unclear if the Dead Hand was even active at this time, and also it probably triggers when impact occurs rather than on satellite detection.

Meanwhile this case was a false satellite detection which, if reported, may have caused a retaliatory launch of nukes.