It’s interesting that Trump and his team were challenged at Arlington for breaking federal law, prior to his campaign ever posting video from the event. Never mind that the photographer(s) were invited at the direction of the Gold Star families, the lady on site who tried to stop the filming couldn’t have known that the video would be posted by Trump’s campaign so how could she claim at the time that it was violating Arlington’s restrictions on political activity? Even if you want to argue that posting video later on is a political activity, simply filming is not a political activity.
I helped the Trump campaign with Sarah Root’s family and their number one concern was always making sure her family felt comfortable with activities that they participated in. I would suspect the Gold Star families were similarly briefed and given options on their participation.