Some students complained. His course was meant to be icing on the cake and not to be taken too seriously. It was important to maintain enthusiasm. Where wishful thinking takes precedence over the pursuit of truth, however problematic that pursuit may be, the ethical foundations of teaching are undermined. It is immoral to demand of one's students what one will not do oneself.
Every first grader knows that.
One of the most important results of education, observed Thomas Huxley, is the ability to face unpleasant facts. By this measure, some prospective teachers are not being well-educated. Various technical occupations can be performed by the ethically indifferent. But the moral substrata of good teaching requires those who would claim expertise to exhibit certain virtues. They must show not only pedagogical expertise, but the recognition that the moral issues at the heart of education are no mere matter of that expertise.