How to apply a Views filter to show fields if a radio button is not FALSE? I have a custom field that is a radio button (from CiviCRM), and I made it available as a filter by implementing hook_views_data().

I'd like to apply a filter to show fields if the radio button is set to true; in other words, if not == false.

I feel like this should be possible without using the Views PHP module, but I have hit a wall.
Often these kind of things come back to deciding how best to bend your requirements to suit the available logic. If I understand correctly, you have a radio button with the value of true, but no other options.

My immediate thought is to change it from a radio to a checkbox and set a default value as false (unchecked).

That way you just need to check for if true or if false and you don't need to concern yourself with if not false which does get tricky.