This gist was writen in 2012 and it was solving specific problem in Rails & SimpleForm. Some fellow developers were pointing out this may be out dated concept. That's why I advise everyone to read comment section bellow to have a full grasp of alternative solutions
other sources that may be helpful to understand why this may not be best idea:
Please close this gist man, It creates so many issues, i start to see this code into a lot of places, create pr to ruby if you think it's a right way to handle booleans. Thanks a lot!