Fred Johnson immediately got to work investigating the job after it went wrong, and when he was convinced he was working for the wrong side, immediately dedicated himself to working to make amends. He continued to do this for years (decades?) all while making himself a progressively bigger target when just looking the other way from the start would have served him very well. He was never a villain. He just worked with limited information in his backstory. And since then basically everything he does is aimed at the betterment of the belters/humanity. His early victims probably would have forgiven him relatively quickly if they saw what he was doing afterwards and knew the initial setup. They cared about the cause more than their own lives after all.