Was Mordechai right for allowing his, "seeking the good of his people and speaking peace to all their seed," to interfere with his Torah-study?

Yes! But, because he was a Jerusalemite, who, "Because they were pious, a blessing was given within their Torah," and, "They were successful in understanding and become wise immediately."

As chassidim of our Rebbe, we too are asked to take from our spiritual time to, "seeking the good of his people and speaking peace to all their seed."