One day Dogen instructed, "When someone asks about the dharma or the essentials of practice, you must reply on the basis of the true dharma. Do not answer on the basis of expedient means that are not true, thinking the person is not a vessel of the dharma, or is incapable of understanding because he is only a beginner."
I often get questions about Zen that, although sincere, make sense only in the context of other belief systems. For example, I've been asked how Buddhists receive forgiveness for their sins, or how we can be sure that our next life will be a happier one. Since the very nature of the question indicates that the asker either won't understand or won't be receptive to the answer, it is tempting to give a short but misleading answer and be done with it. But in the spirit of a true Bodhisattva, even if a person is following another spiritual path and asks a question that makes sense only with regard to that other path, we should reply on the basis of the true dharma. This is the way the Buddha taught during his lifetime.
A provisional answer as an expedient means is really of no value. I remember asking, back when I was a newcomer, what the five aggregate were, and a senior teacher told me they were the five senses. It was a short answer and ended my inquiry quickly, but when I later learned that the true answer had little to do with what he had told me, I both resented the senior for his dismissive attitude and ultimately came to distrust his teaching (fool me once, etc.).
Ultimately, only the final true teaching is beneficial. Therefore, without being concerned with whether the person can grasp it or not, we should answer only on the basis of the true dharma. When we're asked a questions, we should value the person's true virtue, and not judge them on status, outward appearances, or superficial characteristics.