> At the same time there is a different dimension to jailing political leaders, which is why Nixon was pardoned.

Nixon was pardoned, but he also resigned and quit politics.

Political leaders are easy to replace, which means that the bar for replacing them should be low. If a leader is accused with crimes and the charges seem plausible enough, they are expected to resign to avoid a divisive trial. Similarly, unless the charges are particularly serious, the other side is expected to pardon the accused. Then the former leader is expected to quit politics and stop being a problem.

This all happens, because political leaders are supposed to care about national interests. Granting a disgraced leader a dignified exit and a chance for a peaceful retirement is often a good idea, as long as the former leader agrees to remain a former leader. On the other hand, pardoning active politicians is about as bad idea as anything can be. That way you get entitled leaders who consider themselves above the law.