If two divers are a buddy pair, they must have agreed beforehand how the dive is going to look. The diver without a camera will take it upon himself to stay with the one who has. Otherwise we're not talking about a buddy pair, we're talking about two friends on the same dive.
If the DM is guiding these two divers only, especially if the dive has been bannered as a refresher, the DM will ensure he remains in contact with the divers. If it becomes clear that the two divers in the "buddy pair" have different and incompatible ideas about how the dive should progress, the DM will attempt to mould their diving to something he can work with. If he can't then he should end the dive.
A camera should only be used by a diver justifiably confident in his diving in that area and those conditions. If the refresher is at a very basic level and covering basic diving skills the diver should not have a camera with him, and the DM should not agree to go with him if he insists on the camera.
If the DM is guiding these two divers only, especially if the dive has been bannered as a refresher, the DM will ensure he remains in contact with the divers. If it becomes clear that the two divers in the "buddy pair" have different and incompatible ideas about how the dive should progress, the DM will attempt to mould their diving to something he can work with. If he can't then he should end the dive.
A camera should only be used by a diver justifiably confident in his diving in that area and those conditions. If the refresher is at a very basic level and covering basic diving skills the diver should not have a camera with him, and the DM should not agree to go with him if he insists on the camera.