Though Plato sides with Socrates against Athens in the Apology he doesn't present his beloved mentor as an innocuous teacher of moral pieties. Had he done so, successive generations would've been asking themselves why such a harmless man was indicted in the first place, let alone put to death.

But Plato is at pains to give us a rounded portrayal of Socrates and this means, among other things, showing us exactly why he was regarded as so dangerous by such a large segment of Athenian society.

In the Apology, Plato doesn't suggest that he disagrees with how Socrates led his philosophical life. However, in the Republic he puts into the mouth of "Socrates" his belief that philosophy is not necessarily a good thing under certain circumstances. If young people become aware of philosophy at too early an age then they are liable to start questioning the truth of the moral precepts handed down to them by their parents. As a result, the very foundations of society will be undermined. In such cases, philosophy will be seen as a dangerous and disreputable pursuit.

This relates to one of the charges leveled against Socrates during his trial: that he corrupted the youth of Athens by philosophy. Although, as we've already seen, Plato supported Socrates during his trial, he nonetheless acknowledged that philosophy, the examined life, could have dangerous consequences for society and its traditional system of morality.