Default UI state for PropTypes.bool props always render to true (switched on) regardless of the defaultProps of false.

Looks like this line is relevant:

const defaultProps = this._properties[prop] || values;

this._properties[prop] is either false, the value from the component's defaultProps, or undefined because defaultProps aren't accounted for here (if I understand this piece correctly).

So it falls back to the default value which is true for PropTypes.bool.