It doesn't matter if it was one comment or 17. If the intended audience is stating how the interruption is impeding their ability to communicate freely, which you can see from the students' response in the article, then yes, it's interfering and it is a problem.

Her job is not to attend events and call out things she disagrees with. It's also not her job to call out decisions on her own; that's why there's an entire board. Her role in this situation would be to address it at a board meeting, where the entire board is able to communicate about it. The board has legislative authority over the district; they do not have the authority to disturb educational sessions at an off-site event. She had no right to interrupt the session, regardless of her position on the board.