What happened to the builders of the Tower of Babel will happen to them. Allusion to Genesis 11:1-9.
He has already done so: it's Simon the Zealot speaking. The conversation then continues. See next note.
Book of Genesis 11, 1-9
Gn 11, 1-9 : All the earth had one language and the same words. When the men set out from the East, they found a plain in the land of Sennaar, and they settled there. They said to each other, "Come on, let's make bricks and bake them in the fire. "And they used bricks instead of stones, and bitumen instead of cement. Then they said, "Come, let us build ourselves a city and a tower whose top is in heaven, and let us make ourselves a monument, lest we be scattered over the face of all the earth. "But Yahweh came down to see the city and the tower that the sons of men were building. And Yahweh said, "Behold, they are one people, and they have for themselves all one language; and this work is the beginning of their undertakings; now nothing will stop them from accomplishing their plans. Come, let us go down, and there confuse their language, so that they no longer hear each other's language. "So Yahweh scattered them from there over the face of all the earth, and they ceased to build the city. That's why it was called Babel, because that's where Yahweh confused the language of the whole earth, and that's where Yahweh scattered them over the face of the whole earth.