It's a lot more likely that someone was watching the video feeds and saw all the same shit we saw, that some asshole was making faces, not smiling or clapping, and shaking his head and saying no when POTUS was making points.
They nabbed him down, then after getting a chance to talk to him they came for his friends too.
You don't think they have a plan in place in case someone tries to subtly make faces or gestures behind POTUS?