The adjective which best describes the image in the poster is repressive.
A thing or person is said to be repressive if their actions inhibit or restrains personal or collective freedom.
An audience is most likely to reject the thought of being enslaved or having their freedom taken away. This is because it inspires fear.
The propaganda technique used in the poster is called Appeal to Fear.
Appeal to fear propaganda technique is used to elicit support by creating fear, anxiety, and or panic in people. This works because the nazi symbol there represents the social and political exclusion of all that is not German and a totalitarian movement.
Learn more about propaganda techniques in the link below:
propaganda techniques