I chose the New Vegas and McCarren option, aligned the reflectors and was instructed by the mission to go speak to Ignacio again. When I go to him, he doesn't have any new conversation options and I cannot complete the mission. Killing him will complete it and reward me the XP, however. If I choose to overload the plant, I can speak with him and complete the mission as well. But I can't complete it using the option I want to use without killing Ignacio.