I think raising questions over whether or not instructors should train like everyone else is undoubtedly a worthy topic for self-contemplation -- not just for instructors but also for everyone. Simply because in the process of such contemplation we may "rub up against" current personal and/or socio-political relationships that carry some weight in our lives, reflecting deeply as an individual upon this topic does not become meaningless and/or without merit. If contemplation forces us, by the natural consequence of association, to reflect directly upon a person we may know, such matters are not reduced to mere matters of personal condemnation and/or personal uplifting. I think this is an important matter to consider, of course for oneself, but also for those that currently train under us and/or will one day. We do not satisfy this importance by lifting up one teacher and/or by denouncing another. Those actions are beside the point. Every teacher's pedagogy has to have a symbiotic relationship between "what is best for oneself" and "what is best for one's students." Such contemplation is simply part of that whole process -- it is not a personal attack upon anyone and/or a proscription upon everyone's behavior.
Before running my own dojo, I had been a regular student (i.e. training daily) of eight teachers, with four of them shihan. Out of all of them, only three participated in training as we are all beginning to understand it. These three were shihan. They were also self-admittedly "mavericks" of sorts. That is to say, they knew that most folks of their stature did not "train" like everyone else. Such a sense of being different is, I believe, a mark of a kind of paradigmatic shift -- one we may all be a part of at some level.
20th century martial arts training, in Japan and especially as it traveled abroad, was heavily influenced by types of thinking that supported the practice of teachers not training like everyone else. To be sure, there were all kinds of practical reasons for such a course of action, but there were also discourses like Neo-Confucianism that did a lot for making "not training" appear to be perfectly okay. Consequently, questions for contemplation such as these were not really considered at that time, and instructors that did train as everyone else were not considered mavericks, either by themselves or by others.
Things have changed over the last century and into the current one. In particular, training in Japan, especially Aikido, have come to steer away from discourses like Neo-Confucianism, and training is more and more becoming akin to exercise than it is to other forms of spiritual practice. As "exercise," the moving and not moving of oneself comes to take on a different meaning than when such things were directly relevant to one's position in institutional hierarchies (e.g. a martial ryu). In Japan, increasingly, you are either exercising or you are not, you are either training or you are not. It is my opinion that this is one reason why you see more older and higher ranked aikidoka (men and women) simply doing class like everyone else in Japan, versus a place like the United States.
Something else has occurred, in my opinion, in the areas that arts like Aikido spread to. The general practicing population of these countries, while tending not to see the art as mere exercise, also tend not favor the original discourses that supported the action of instructors not training. Hence, 20th century reasons of practicality for instructors not training are raising more questions than they are settling in these areas as well. 20th century rationales, whether they were correctly understood and/or misunderstood, are being replaced by notions that stress and equate moving with doing, doing with being, and being with legitimate practice. Such rationales come to the general training public via things as mundane as Nike's slogan, "Just Do It," but also through things as profound as accurate understandings of Budo, Buddhist, and other spiritual traditions relevant to martial arts training -- which is finally disseminating properly to areas outside of Japan -- and that are combining with modern notions of social equality. The combination of these properly understood ideas and social egalitarianism are making it increasingly difficult for instructors of today to say they train when they are not training like everyone else. This occurs in the same way that folks in Japan find it difficult to say they do Aikido when they are not exercising with Aikido like everyone else. In other words, there is a growing social and cultural pressure to not excuse oneself from the mat.
To be sure, trends are never complete. Moreover, trends are never without their competing trends. Therefore, what is important to note is how there was once a time when questions for contemplation such as this one wouldn't have been possible -- how we have traveled to a time when they are not only possible to ask but also to a time when it is most probable that they will be asked. Personally, I think that is a good thing. I think that is just one more step in the right direction. After all, moving is doing, doing is being, being is having a legitimate practice -- but this is just my time speaking.