On a superficial level, McLuhan's stance against moral judgment appears to be in opposition to other media ecologists, notably Neil Postman, certainly Jacques Ellul, also Lewis Mumford, and even Harold Innis. But I think that McLuhan was not ruling out the possibility of evaluating media and technology, and indeed saw such evaluation as something that was sorely needed, that we have to learn how to contemplate the consequences of our innovations in order to take control back from our technologies, or else what could this quote of his mean?: "there is absolutely no inevitability as long as there is a willingness to contemplate what is happening" (from The Medium is the Massage, 1967, p. 25).
What McLuhan was protesting against was the uncritical rejection and condemnation of media and technology, and the corresponding uncritical acceptance and celebration of media and technology, both the moral indignation of the technological idiot and the narcissus narcosis of the gadget lover, to use McLuhan's words. His point, I believe, was that we need to withhold judgment until we have made an adequate assessment of the effects of innovations, otherwise our prejudgment would influence, bias, and cloud that assessment.
And it may be that McLuhan didn't feel that media ecology had progressed far enough back in 60s and 70s to provide a good enough understanding to draw any conclusions, but it certainly has come a long way since then. I think Postman, Ellul, Mumford, and Innis would all agree that understanding must precede evaluation, even if they felt that they had achieved sufficient understanding to come to certain conclusions.
I also think that McLuhan was looking for scientific validation, even while resisting having his work judged by scientific criteria (for example by objecting to being called a theorist). Science was the main source of intellectual legitimacy in his day, I believe that McLuhan, Ong, and Postman all had a healthy respect for scientific fact while distancing themselves from scientistic language and perspectives, and McLuhan was claiming a bit of that legitimacy in maintaining his objectivity in regard to the phenomena he was studying (scientists don't make moral judgments about subatomic particles or chemical formulas or biological functions, although scientists do have ethical standards and values concerning knowledge, truthfulness, etc.).
A further function of McLuhan's position is that it created ambiguity, something he would appreciate as a literary scholar. It made him a cool medium, and let others fill in the gaps. By not taking a stand, it became possible for both critics and boosters of media and technology to claim him as their own.
In an essay I wrote for an upcoming issue of Educational Technology magazine on the neutrality of technology (my position being that technology is not and cannot be neutral), I explained that while the question of whether a given technology is good or bad may be problematic, it can be reframed as, can a technology be evaluated within and according to the criteria of a given moral or ethical system?, and the answer to that question is, of course it can! Within some ethical systems, all violence is bad, so weapons can be evaluated as bad, for example, swords and spears are bad, plowshares and pruning hooks good. Firearms can be evaluated as bad, and as for nuclear weapons? Fuhgeddaboudit!
And apart from morality and ethics, we can also engage in more utilitarian forms of evaluation, and assess whether a technology is functional or dysfunctional for individuals, a given society, humanity, or the biosphere and planet.
To arrive at such conclusions, we do have to weigh the services and disservices, to use McLuhan's terms, that is, the costs and benefits, the positive and the negative consequences. And that may be a difficult task. It may be impossible to do so definitively, because there will always be unintended consequences that are also unanticipated, and there are indirect effects, which lead to other indirect effects, which lead to others, etc. But even if we cannot be entirely certain of the outcome of introducing an innovation, we still can retain human agency and exercise judgment, and decide whether we ought or ought not to use the new medium or technology. (That is if we hold aside Ellul's arguments about the technological society.)
On the specific question of teaching about morality and media, I think introducing a course in ethics of new media is commendable, and some consideration of the ethical dimensions of any field or subject ought to be a curricular requirement. That is, if our educational objectives still have some room left for the goal of producing responsible citizens and well-rounded human persons.