Being an adversary does not mean being an enemy. I rarely have an adversarial relationship with students that is long term and related to rigor, but I have taken classes where the teacher uses this conceit to great effect.
I recall a Shakespeare professor from college who was a master of playing devil’s advocate during discussions. He always challenged students to think more deeply about their assumptions. Students tended to rise to the occasion in this class. The challenging nature of the teacher’s persona aided in our understanding of the texts. (Each student had to lead discussion three times during the term, that’s how he was able to sit back and put the students in the firing line – he never called on people cold or intended to embarrass anyone – but students knew to show up well-prepared on those discussion days.)
When confronted outside of class, this professor was perfectly reasonable. He exercised his adversarial persona with total self-knowledge of why this technique worked for him and for his particular area of expertise.
I would consider the adversarial position, done well, as a persona developed for a specific purpose rather than a natural result of someone’s antagonistic qualities. If a classroom is full of antagonism between students and teachers, if they are behaving as enemies rather than adversaries, then that is more of a classroom management problem in need of a solution rather than a studied technique.
To me, intent is a major factor in how a pedagogy is utilized in a classroom. A teacher knowingly using adversarial techniques, sort of like acting as an opposing counsel in a trial, is much different than a teacher who perpetually fights their students without knowing why.