Why does Les say he teaches so much prophecy?
He teaches so much prophecy because Paul considered prophecy important for new believers fresh out of paganism. If it mattered then, it matters even more now, so believers should teach and know prophecy as they approach the hour. This is the stated reason for emphasizing prophecy.
Les explains that his reason for teaching as much prophecy as he does is that Paul thought prophecy was important in his day to those new believers fresh out of paganism. Therefore, he reasons, it is even more important for us to teach it and to know it as we are approaching the hour. The surrounding passage then moves to the restraining power that keeps the Antichrist from being revealed until God's time.