One can certainly be politically liberal and be orthodox in their beliefs. One can also be conservative and be heretical. It is unfortunately true in the real world that one who is politically liberal is more likely to be a supporter of questionable theological stands. That, at least, is my experience. Why is this?
My belief is because both those who are liberal and those who are dissidents from Church teaching have in common a lack of historical perspective. John Henry Cardinal Newman once said, "To be deep in history is to cease to be Protestant." Many if not most of the changes that Catholic dissidents desire are changes which some Protestant denomination somewhere has already tried. Starting with denial of the primacy, and infallibility of the Pope and the Magisterium to the ordination of women some Protestant group has already tried it. Indeed at its heart any Catholic dissident movement requires at its heart a denial of the teaching authority of the Church.
Not to be misunderstood, conservatives are just as capable of taking a stand in opposition to Church teaching. How many otherwise faithful Catholics argued that waterboarding was alright because we got "useful information that prevented another terrorist attack"? A stand which denies Church's teaching on the principle of intrinsic evil.
Intrinsic evil refers to actions that are morally evil in such a way that is essentially opposed to the will of God or proper human fulfillment. The key consideration here is that intrinsically evil actions are judged to be so solely by their object, independently of the intention that inspires them or the circumstances that surround them.To support torture is to support an intrinsic evil and is in most cases a sin. As for all such cases support must be proximate, that is it must be an actual effective support for the act, not an unintended consequence.
So how does this touch the catechist? The mission of the catechist is to teach what the Church teaches. A catechist who teaches at odds with the teaching of the Church corrupts souls. He leads others astray. Millstones come to mind, along with other ultimate unpleasantness for the individual catechist, as well as for any others who knew and supported such acts, even if only by a sin of omission.
All are sinners. At least all of those left in this land of exile. No matter how faithful the Catholic there is almost certainly some Church teaching which grates. It is the duty of the catechist to ignore their personal feelings on the issue and teach what the Church teaches. That is our ministry.