This is especially true of the homily. The assembly, the gathering of the people of God in celebration, as a sign , as an actual expression of church. Through this assembly, the Church appears before the world, bears witness of its presence as a royal, prophetic, and priestly people, intent upon the worship of God and the renewal of the world. Liturgically, we are bound by time, space, gesture and artifacts. The dynamics of those elements, when referring to unity, demand a physical manifestation of unity, i.e. all present.
Children have the right to assembly, by virtue of their baptism, and ought therefore to remain.