We don’t know about the requirements of attendance either. What if their home wasn’t safe at the time and splitting up the Secret Service and having them go a different route with traffic would have been dangerous. Maybe even threats were made c”v. So for their safety they needed to just move along together in front of cameras.
We can have quiet Shabbats at home Baruch Hashem. For Jared and Ivanka, who knows what would have been banging on their doors or happened had they tried to lay low for Shabbat. Maybe this atypical Shabbat heter was permitted to allow the family to observe the rest from here on out in peace. Or more peacefully.
We can be grateful that we don’t have such complicated Shabbat scenarios.