There was a thread on this site a number of years back that talked of this subject. I remember reading about one instance where the paramedics were called to the KH to assist a dying JW and a sister in the audience started handing tracts to the paramedics and witnessing to them (all while the meeting continued on)
Another example of witnesses refusing to interrupt a meeting was back in the 70's in Chicago. The PO was Norman Zenke and he needed to give an additional announcement to the MS who was announcing the weekly announcements from the platform at that very moment. Instead of walking up and handing the MS his little piece of paper with the new announcement, he gets on his hands and knees and crawls up to the stage and stretches out his arm to give said announcement to speaker, and then crawls on hands and knees back to seat.