Think about what Best Jeanist said about Kacchan: "But if these strong feelings were directed towards something else..."
You may see patterns, especially since the author admitted Kacchan's reasons for being #1 hero were fleeting, himself. I think Best Jeanist noticing that was neat, but if you look well into his words, I think you see where I'm getting at with the set-up. This is setting up Kacchan being abducted at the Summer Camp, and coerced into villainy at Kamino.

Then there's Gunhead teaching Ochako how to avoid knives. This sets up the scene where Ochako avoids Toga's knife at the Summer Camp.

And then Tsuyu learns that team trust and following the leadership is the right thing to do. It's the moral thing to do. It's the heroic thing to do. And what the boys did in Hosu, and ... in Kamino, during the Hideout Raid Arc. And she crying in front of the students that chose to act on their own, making an analogy between their behavior and how a villain would act. This is in-line with what's being discussed in this episode clearly.

In my opinion, this episode was a platform for what is to come. I doubt it served as mere fanservice. I think this was actually thought out, more than the OVAs.