TBF, the instructor has been given a very difficult task. Much like the old SCOTUS line about porn. "I know it when I see it" it is increasingly difficult to measure "extremism because we are wrapping it too deeply in our personal political feelings. In the class the examples used were low hanging fruit (guys who swithced to radical Islam and threatened soldiers and one guy who joined the American Nazi Party and put a noose on another's bunk) and everyone saw that. Still, when one person conflates their political views against another's religious views (as an example) people tend to jump right to "extremism" by way of "you" don't agree with "me" so "you" are an extremist because "I" am the most reasonable person in the world.
Not an easy task for any instructor. I will note that our guy is a member of Space Force and used the term "guardian" which I thought was extreme. ?