Was it right to avoid leading the prayer after the worshippers requested it, in order to avoid discord with the assigned imam, or should one have led the prayer despite the presence of someone who did not perfect the prayer in his place?

If the mosque was built by the state or endowed by some individuals, the appointed Imam has the right to delegate someone else, and his deputy would have a stronger claim to lead the prayer if the conditions are met. However, if the mosque was built by the mosque's congregation, the Imam does not have the right to delegate someone else. In this latter case, if the Imam is not entitled to delegate someone else, then the correct action is for you to step forward to lead the prayer, and the congregation's dislike of your imamate will not be harmful, unless it is due to a religious impediment.