A few news sources have been reporting on Ivanka Trump and Jared Kushner's having been granted rabbinic permission to drive on Shabbat after Ivanka's father's inauguration as president. (See, for example, here).
Without knowing any of the details surrounding this (such as who was the posek), what are the sorts of circumstances that might have been factored in? The article in The Forward mentions their "safety", but doesn't elaborate as to how this could possibly be a case of pikuach nefesh. Might there be other factors as well?