Assuming for one moment that telling someone to follow their conscience in a specific instance is wrong, (and it is never wrong to follow one’s well-formed conscience), do you really think God would send someone to hell for following advice they accepted in good faith from someone in a position to give it, but that was erroneous to begin with? Similarly if a priest erred in some piece of moral advice to a penitent (and to err is human), do you really think that following it would condemn someone to hell? Would not the sin rest with the person giving the advice rather than he or she who follows it? And if the priest committed the sin of giving wrong advice in good faith (for example misunderstood someone with a thick accent), would he be condemned to hell for it? Does God convict us to eternal punishment on a misunderstanding?
If it were the case that following wrong advice sends the recipient to hell, then the whole sacrament of confession would fall apart: a priest could, for instance, advise someone that their culpability is not mortal and that they don’t need to confess a specific sin every time it occurs (this happens). If the priest erred in that judgment of culpability, in good faith, do you think that God would condemn both the priest and penitent to hell for following it? If He did, the confessional would rapidly become a torture chamber and not a place of healing and reconciliation, and contrition, far from being perfect, would become based on fear of the consequences of a mistake.
Strange kind of “loving” and “just” God!!!