The plot of the show is that the people around Cole want to change the past so that the disease never happened. Later during the first season they kind of resignate (especially Jones) and it is often stated that the past cannot be changed and that they all only fullfill their destiny.
While I can understand the resignation because of continuing setbacks, they should know better than to believe that the past cannot be changed. They already did it several times. In the very first episode Cole damages the glass on Cassys clock, and the version from the future follows. In one episode Cassy dies and the Future is changed completely until Cole repairs it.
So why is everybode believing (especially Jones) that it is not possible to change the past?