I am tired and bored.
But we’re talking about a protest where bad actors (the police) just want the names of its attendants. Our phones scream to everyone “I am [name surname] and I am here!”. Bluetooth instead says the same but with a lower tone of voice, so less people can listen. Also, with little configuration you can instruct it not to broadcast its identifier.
What is unsafe about cell communication is that there is virtually no way to prevent being tracked. Bluetooth is not necessarily more secure but has several advantages:
May I ask you how? Or if you have more info? No criticism here, honest question. Afaik the only way to do that would be to fingerprint a behavioural pattern, which albeit possible is surely more secure than cell communication.