Today, I have seen this question closed as an opinion-based question.
First of all, we should consider the existence of a tag education whose description is: How is physics taught and learned. Teaching strategies, class examples, and demonstrations; learning resources, career advice, etc. Why is there a tag like this if any question related to it would be classified as opinion-based? At least, it seems to me there is a contradiction between the existence of such a tag and the way some users (and moderators) interpret the site policy.
However, I want to get to the heart of the issue, which is the relationship between physics education research and PSE. The description of PSE on the main Stack Exchange page is
Physics Q&A for active researchers, academics, and students of physics
I have difficulty understanding why a question relevant to physics teachers (academics) cannot be formulated on PSE. Taking also into account that there is no specific site for physics education questions (like is the case for mathematics education questions).
In another discussion about the same issue, the suggestion was to create a specific site. That could be fine. However, I think that before the process of creation of a specific site goes on, questions about physics education could be hosted in PSE. If I am not wrong, something like that was done in the past for questions about astronomy.
Of course, the form of the question is important. However, I disagree that every question about physics education automatically triggers opinion-based answers. Physics education research is a well-established field of specialization for physicists, and there is well-established scientific literature containing scientific results, not just opinions. I think that questions and answers remaining inside the perimeter of rationally justified arguments should have the right to appear in PSE. If the majority of the community has a different idea, it should be explicitly stated, and, in that case, I would suggest eliminating the education tag.