He’s trying to approach this rationally, but I think he shouldn’t deny his own existence.
“Your party seems like a group of adventures from a guild that could break off at any time and form their own guild. If left alone, they might grow without your knowledge.” (Naofumi)
Wait, that’s brilliant.
That level party. If it grew, we might have an effective army to combat the wave.
It was a random idea, but it might actually be effective.
Now that I think about it, there is no real need for us to do anything. This world’s adventurers can work something out.