A meeting at the UN is supposed to split blame for the violence in Syria between the government and the people. The meeting aims to end violence. Either there will be peace or not, if not then violence.
No reason can be given to explain why the UN meeting is going to take place. The point is that Syrian action follows anyhow whether in peace or violence. Even the great peacemaker, Jesus Christ, tried to opt his disciples into one of several alternatives but failed to do so because of his principlism. Actually the inner purpose of peace is null.