Piper misses a couple crucial things in this sermon.
First, he misses (or at least doesn't mention here) that Jesus was God, as the first eleven verses of John's Gospel clearly indicate. Hence, God the Father (Jehova, Yahweh) placed a part of Himself in Mary's womb that was subsequently birthed as Jesus Christ. Hence, God delivered up a part of Himself on the cross for the forgiveness of the offences we had committed against Him.
Secondly, Piper gets it wrong in that the purpose of the resurrection wasn't because (or just because) Jesus had been dead long enough to pay for the sins of mankind. Rather, (or maybe additionally), it was because if Jesus, who was God the Father (see above) had stayed dead for eternity as man deserves to, then that would have made Christ not the God of the universe but, instead, a mere man like every other person, or at most a God like the Greek gods, Norse gods, etc. who was more powerful than mere human beings but could still be killed the same way people could.