I said nothing about "avoiding defending positions unless they are in line with institutional orthodoxy," whatever that phrase means.
And here we get to the heart of the problem: it is clear that your ideological blinkers are strong and effective. Were they not, that phrase would be clear to you as a high-sky day, and that this really is your position. The paragraph with which I began ("As to the rest of your hypothetical scenario...") clearly delineates some aspects of Valpo's institutional orthodoxy, things not to be said, questioned, or perhaps even thought. Peter is entirely right: for you, things not in line with institutional orthodoxies are heresies, things which are unable to be thought, and you cannot for a moment understand ("I can't imagine") how anyone might agree with or hold them, because they are not Right Thought — there is something wrong with someone spouting them, for to hold them is to be a propagandist, a bigot, or mentally impaired. This is not how the Academy has traditionally functioned, but it is how dissidents were dealt with under Stalin's heirs.
Your fear of "shut[ting] down the learning process" leaves your students with method, and nothing more. A useful method, to be sure — differing positions should be examined and investigated, and learning to deal critically and logically with texts, facts, and arguments is essential — but one that does not give the tools to do more than agree that one take on a matter is less strong than some others. What is missing here is an understanding that perspectives are merely another piece of data, and have no value in and of themselves except as another angle from which to view something; while in some cases we might not be able to see clearly just what the truth of something is (in the "black-and-white" sense), we
can substantially narrow things down after subtracting, among other things, the prejudices that those differing perspectives bring to the table. If all you have or end up with are "perspectives" and "views"...then there's no point in helping your students examine varying perspectives, unless your job is simply to help students practice proper method. if that's the case, then by all means, keep at it.