Sorry, I'm not sure I follow. Why would travel back to a time they were already at where they'd most likely run into their past selves, instead of forward to try and start a new civilization and hopefully finally be free of all the Sburb and LE bullshit

They traveled into the future to get there so the most logical course of action would be to travel back to right after they left so it’d be like they were never gone. and Caliborn was the last piece of Sburb/LE bullshit they had to deal with so after beating him they could live the rest of their days in relative peace.