I think you are correct that the danger with negotiations is that they, too, can drag on. We would be limited in how many could be sent for that exact reason - minimal disruption. Who was selected would matter as well, in terms of whatever value reducing incredulity at their presence might provide.

If they take themselves elsewhere, that will heighten Chantry pressures and protests - they already fear the rifters and what they might do. And if the rifters stay together in their departure, we might not see them return, should there be enough of them together that the shards not cause them distress. Furthermore, those who are loyal and stay could be the ones who suffer for allowing a mass departure, if their shards begin to cause them pain from the reduction in numbers. That would be unjust.

I agree that moving forward efficiently in necessary, but I do not think negative reinforcement will do anything to ease tensions.