New Covenant people

By using your logic, we could say that God only meant that command for the Old Covenant people, but not for the New Covenant people.

Peter is able to describe the church like this because she is the new covenant people of God; he gathers his church together, and in her gathering she expresses her identity as his precious people.

The New Testament writers understand this event typologically: as the lamb's blood saved the Israelites from the plague, so Jesus' substitutionary death saves God's New Covenant people from being judged for their sins.