Normally the GC neutralization, which is what defines the start of the "safety zone", from that point until the finish, where the GC times are taken, is at 3km to go to the line. A timing device and a Commissaire are set up there. GC time is set by the group that you are in at that point. That is the UCI regulation. This is why you will see GC contenders up at the front of the race close to the finish, surrounded by teammates, so that they get to that point safely, and get the same finish time as their GC rivals. However, organizers are allowed to change this, usually at the morning safety meeting, to something a bit farther out, like 5km. This is why you will see different safety zone points in different races or stages.
What happened yesterday was a group of GC contenders, one at a time, dropped back to the Commissaire/Organizer car (red car, Commissaire 1) to discuss the neutralization point. I don't know what was said, but at least Campanaerts, Hindley, O'Connor, and Jonas each had a conversation. Different points were discussed. This is not rare, but the end of the race is not the best time and place to discuss the finish for the GC riders when the finish is minutes away. It causes a lack of focus and confusion for the riders and their DS. Since the finish was on a circuit, they eventually decided to take the time at the line on the bell (last) lap of the (9.7km) circuit. After that point, in the middle of a chase to catch the break, GC riders and their teams were drifting back to get out of the way. I heard that there was one crash between that point and the finish, but I don't know who and when.
There are times when course changes on the road make sense. A typical one is if the race is underway, and a thunderstorm with lightning is suddenly closing in on the race. The race can be stopped to let the riders take shelter. The finish line can be moved to an intermediate town along the way. The course can be rerouted around the storm, as there is always a parallel route to the course that race vehicles, like team buses, can use. With a criterium or circuit race, the number of laps can be reduced on the fly and the bell rung earlier. However, I am not in favor of these rider "protests". I saw nothing unusually dangerous about that circuit or the 3km point. If it was such a big concern, it should have been brought up at the safety meeting. I understand that the course isn't really set until the barriers are put up a few hours before the finish. I just did not see the concern from what I saw on tv. Not enough to make a change like that so close to the finish.
Rest day today. Jonas (Visma) has 2:26 on Eulalio (Bahrain), 2:50 on Gall (Decathlon), 3:03 on Arensman (INEOS) , 3:43 on Hindley (Bora), and 4:22 on Pellizari (Bora). There are lots of tough climbs ahead in the final week, those are some very strong teams.