This is the point I'd really like to know, just how much of what happened during the camping trip are the adults aware of. Shun mentioned that they know that their powers had been sealed, and then obviously unsealed. I'm in agreement with the people suggesting that the sealing/unsealing process developed by the society places controls the cantus users; controls that probably were not replaced when they unlocked their own powers using Saki's method. If that's the case, then these kids could probably kill other humans. With the society knowing this, I'd have expected a much more pronounced and immediate reaction from them. That's not what we're seeing though. They're behaving as if Shun is a "normal" threat whose restraints are still in place.

This is of course assuming everyone is correct about the restraints and their implementations.