It's a typical Daily Mail bullshit story. Mazlan Othman is the director of the UN Office for Outer Space Affairs. That means she heads up the team that negotiates treaties and laws between countries for the cooperative exploitation of space and that sets out policies for dealing with satellite debris etc in earth orbit.
She made a speech recently where she said that if there was any need in the future to have a spokesperson for Earth as a whole in relation to contact with aliens, then the UN would be the best organisation to handle it (which makes sense - who else should do it?) She hasn't been appointed to any "space ambassador" position though because no such position exists. She was just talking hypothetically.