Nope, as mentioned in the opening post, it was deleted inside of the editor with the content browser’s delete function.
Also the explanation doesn’t explain the problem because the problem was indirect referencers were being indicated as direct referencers in the reference viewer as shown in the picture.
In stock engine it is not possible for a MIC to directly reference a Regular Mat Func. It can only reference other asset types that can directly reference regular mat funcs (Materials, Layer/Blend Funcs).