AITAH for calling out my boss for hazing our co-worker?

We all work in veterinary medicine; licensing/education is critical. My boss and I are licensed technicians; obviously, he's my senior with more experience. We work in a small town general practice, so staffing is challenging to find. Our co-worker will call her Nancy, who has the education but not the license, at least, not yet. Nancy has shown interest in getting her license. To get it, you take a very expensive, thorough exam. It costs close to $400 to take the national exam.

Since Nancy showed interest, our boss, whom we will call Chad, has constantly pressured her to take the exam. Chad asks daily when her test date is and tries to train her on how to do our duties before she's licensed. This has put a lot of pressure on Nancy, which she's admitted verbally to our staff. Nancy has shown extreme anxiety in learning these licensed tasks since it's been a decade since she was in school. It got to a point where I stepped up since no one else had said anything to Chad that he was practically hazing Nancy to take her exam and to stop the constant pressure for her to pass. I told Chad that Nancy should study independently and take the test when ready. No one wants to waste $400, especially for a test she can take whenever ready. Also, we are not short on licensed technicians; we have five currently working. If anything, it's assistants we constantly need, which Nancy is. Nancy loves being an assistant and is excellent at her job. Ever since I said something, Chad told me it was none of my business and to back off, telling me I'm not the leader he is. I was livid, but I want to keep my job, so I just walked away and took the high road. AITAH?