Would God then be stuck with this sinless person walking around with nothing to do. 

Or perhaps she couldn't say no, therefore, making all of Salvation history the biggest con-job ever committed and making Mary little more than a sacred cow.

As described by Pope John Paul II, Mary was "spiritually crucified with her crucified son" at Calvary, and "her role as Co-redemptrix did not cease with the glorification of her Son." [ John Paul II, Papal Address, Jan. 31, 1985, Guayaquil, Ecuador, (O.R., March 13, 1985).]

Did Jesus speak on this?

“Be on your guard against false prophets, who come to you in sheep’s clothing but underneath are wolves on the prowl.  You will know them by their deeds.  Do you ever pick grapes from thornbushes, or figs from prickly plants?  Never!  Any sound tree bears good fruit, while a decayed tree bears bad fruit.”(Matt 7:15-17)

What are the deeds of the current Church of Rome. 
 

And the reward for such actions prophesied by Christ?

”You can tell a tree by its fruit.  None of those who cry out, ‘Lord, Lord,’ will enter the kingdom of God but only the one who does the will of my Father in heaven.  When that day comes, many will plead with me, ‘Lord, Lord, have we not prophesied in your name?  Did we not exorcized demons by its power?  Did we not do many miracles in your name as well?”  Then I will declare to them solemnly, ‘I never knew you.  Out of my sight you evildoers!” (Matt 7:20-23)

This heresy of the Immaculate Conception is a sin against the Holy Spirit of God.  Did Jesus say anything about this crime?

“Therefore I tell you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven.  And whoever says a word against the Son of man will be forgiven; but whoever speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come.”  (Matt. 12:31-37)

This heresy of the Immaculate Conception tries to make a fool of Jesus who said:

“Truly, I say to you, among those born of women there has risen no one greater than John the Baptist; yet he who is least in the kingdom of heaven is greater than he.” (Matt.11:7-19)

Evidently Jesus forgot to say, except for my mom of course. 
 

Peter turned around at that, and noticed that the disciple whom Jesus loved was following (the one who had leaned against Jesus’ chest during the supper and said, “Lord, which one will hand you over?”).  Seeing him, Peter was prompted to ask Jesus, “But Lord, what about him?”  “Suppose I want him to stay until I come,” Jesus replied,“how does that concern you?  Your business is to follow me.”

This is how the report spread among the brothers that this disciple was not going to die.  Jesus never told him, as a matter of fact, that the disciple was not going to die; all he said was “Suppose I want him to stay until I come [how does this concern you]?” (John 21: 20-23)

Odd thing to say.  “Suppose I want him to stay until I come [how does this concern you]?  Obviously the immediate understanding during the lifetime of the disciples was a literal understanding of Jesus’ words.  “Suppose I want him to stay until I come” If it was to be taken literally, then John would still be alive today, kicking and telling people to love, love, love.  (And very good advise too.)

But John’s not here.  And neither is Jesus (via His second coming).  Since these words of Jesus was spoken after His resurrection, “until I come” could have no other meaning than Jesus’ prophesy of His return.  His Second Coming.

If Jesus speaks only the truth, then these words of His must be true.  In the manner that Jesus meant them, not as we understand them or even as John understood them.   For John’s earlier quote of Jesus is concerning Peter was: “I tell you solemnly: as a young man you fastened your belt and went about as you pleased; but when you are older you will stretch out your hands and another will tie you fast and carry you off against your will.”

(What he said indicated the sort of death by which Peter was to glorify God.)  When Jesus had finished speaking he said to him, “Follow me.”

Did Peter die reluctantly, never changing from the man who denied Jesus three times?  Or with Jesus’ resurrection, did he acquire a backbone stronger than his brave words on the Mount of Olives.  After all, before the disciples knew of Jesus’ resurrection, they all cowered in the upper room where they had the Last Supper with Jesus, afraid of the Jewish officials.  After Jesus rose from the dead and manifested Himself to his apostles, they braved those same officials in their lair, the Temple of the Old Covenant. (See the Acts of the Apostles)

Therefore, John’s interpretation of this quote of Jesus only makes sense if Peter did not want to die a martyr.  And John did not explain the second perplexing quote concerning himself other than to say it didn’t mean he (John) would be immortal here on earth waiting for Jesus.  “Suppose I want him to stay until I come [how does this concern you]?

Is John still here? Alive and well and waiting for Jesus?  Actually, he is.  In his writings, most particularly his Gospel and in Revelation.  In fact, in a more vital, beneficial way than if he were here in person.  Because with his words, we have the added influence of the Holy Spirit sealed within and waiting for our understanding.

So if John only partially understood Jesus words concerning himself, then he probably did not completely understand the part about Peter.  “When you are older you will stretch out your hands and another will tie you fast and carry you off against your will.”  As John is here today with his writings, so is Peter here today old and withered, within the Chair of Peter, bound and carried off against his will by heresy.
 

Would God then be stuck with this sinless person walking around with nothing to do.

Or perhaps she couldn't say no, therefore, making all of Salvation history the biggest
con-job ever committed and making Mary little more than a sacred cow.