If Jesus had done it or encouraged others to do it, He would have been breaking the Law, thus sinning, and disqualifying Himself from being the pure, spotless lamb of God who could take away the sins of the world.
Jesus knew the cup was wine and said so Himself.
Matthew 26:29 I tell you I will not drink again of this fruit of the vine until that day when I drink it new with you in my Father’s kingdom.”
Mark 14:25 Truly, I say to you, I will not drink again of the fruit of the vine until that day when I drink it new in the kingdom of God.”
Luke 22:18 For I tell you that from now on I will not drink of the fruit of the vine until the kingdom of God comes.”
Don't eat the blood, the life is in the blood
Genesis 9:4 But you shall not eat flesh with its life , that is, its blood.
Leviticus 3:17 It shall be a statute forever throughout your generations, in all your dwelling places, that you eat neither fat nor blood.”
Leviticus 7:26-27 Moreover, you shall eat no blood whatever, whether of fowl or of animal, in any of your dwelling places. Whoever eats any blood, that person shall be cut off from his people.”
Leviticus 17:10-14 “If any one of the house of Israel or of the strangers who sojourn among them eats any blood, I will set my face against that person who eats blood and will cut him off from among his people. For the life of the flesh is in the blood, and I have given it for you on the altar to make atonement for your souls, for it is the blood that makes atonement by the life. Therefore I have said to the people of Israel, No person among you shall eat blood, neither shall any stranger who sojourns among you eat blood.
“Any one also of the people of Israel, or of the strangers who sojourn among them, who takes in hunting any beast or bird that may be eaten shall pour out its blood and cover it with earth. For the life of every creature is its blood: its blood is its life. Therefore I have said to the people of Israel, You shall not eat the blood of any creature, for the life of every creature is its blood. Whoever eats it shall be cut off.
Leviticus 19:26 “You shall not eat any flesh with the blood in it. You shall not interpret omens or tell fortunes.
Deuteronomy 12:16 Only you shall not eat the blood ; you shall pour it out on the earth like water.
Deuteronomy 12:23 Only be sure that you do not eat the blood, for the blood is the life , and you shall not eat the life with the flesh.
Deuteronomy 15:23 Only you shall not eat its blood; you shall pour it out on the ground like water.
Acts 15:12-29 And all the assembly fell silent, and they listened to Barnabas and Paul as they related what signs and wonders God had done through them among the Gentiles. After they finished speaking, James replied, “Brothers, listen to me. Simeon has related how God first visited the Gentiles, to take from them a people for his name. And with this the words of the prophets agree, just as it is written,
“‘After this I will return, and I will rebuild the tent of David that has fallen; I will rebuild its ruins, and I will restore it, that the remnant of mankind may seek the Lord, and all the Gentiles who are called by my name, says the Lord, who makes these things known from of old.’
Therefore my judgment is that we should not trouble those of the Gentiles who turn to God, but should write to them to abstain from the things polluted by idols, and from sexual immorality, and from what has been strangled, and from blood. For from ancient generations Moses has had in every city those who proclaim him, for he is read every Sabbath in the synagogues.”
Then it seemed good to the apostles and the elders, with the whole church, to choose men from among them and send them to Antioch with Paul and Barnabas. They sent Judas called Barsabbas, and Silas, leading men among the brothers, with the following letter:
“The brothers, both the apostles and the elders, to the brothers who are of the Gentiles in Antioch and Syria and Cilicia, greetings. Since we have heard that some persons have gone out from us and troubled you with words, unsettling your minds, although we gave them no instructions, it has seemed good to us, having come to one accord, to choose men and send them to you with our beloved Barnabas and Paul, men who have risked their lives for the name of our Lord Jesus Christ. We have therefore sent Judas and Silas, who themselves will tell you the same things by word of mouth. For it has seemed good to the Holy Spirit and to us to lay on you no greater burden than these requirements: that you abstain from what has been sacrificed to idols, and from blood, and from what has been strangled, and from sexual immorality. If you keep yourselves from these, you will do well. Farewell.”
12. What are the Words of Institution?
Our Lord Jesus Christ, on the night when He was betrayed, took bread and when He had given thanks, He broke it and gave it to the disciples and said: “Take eat; this is My body, which is given for you. This do in remembrance of Me.” In the same way also He took the cup after supper, and when He had given thanks, He gave it to them, saying: “Drink of it, all of you; this cup is the new testament in My blood, which is shed for you for the forgiveness of sins. This do, as often as you drink it, in remembrance of Me.”
13. Do you believe, then, that the true body and blood of Christ are in the Sacrament?
Yes, I believe it.
14. What convinces you to believe this?
The word of Christ: Take, eat, this is My body; drink of it, all of you, this is My blood.
15. What should we do when we eat His body and drink His blood, and in this way receive His pledge?
We should remember and proclaim His death and the shedding of His blood, as He taught us: This do, as often as you drink it, in remembrance of Me.
The Little Catechism-Martin Luther