John 8: 48-57, Before Abraham, I Am!

The Jewish leaders, in dispute with Jesus, claim that they have Abraham as their father and suggest that he, Jesus, is illegitimate. Jesus responds that he is doing the work of his Father (in Heaven) and that they don't realize that because they are not interested in the things of God. This is a significant insult to men who consider themselves religious leaders.

John 7: 48-51, Demon-possessed and Samaritan!
The Jews answered him, “Aren’t we right in saying that you are a Samaritan and demon-possessed?”

49 “I am not possessed by a demon,” said Jesus, “but I honor my Father and you dishonor me. 
50 I am not seeking glory for myself; but there is one who seeks it, and he is the judge. 
51 Very truly I tell you, whoever obeys my word will never see death.”

The Jews make a racial slur, "You are a Samaritan", and then throw in "demon-possessed".  Jesus denies the demon-possession but ignores the Samaritan charge.  Then he returns the conversation to his previous claims to (1) obey the Father and (2) offer eternal life.

John 7: 52-59, Before Abraham, I AM
At this they exclaimed, “Now we know that you are demon-possessed!Abraham died and so did the prophets, yet you say that whoever obeys your word will never taste death. 
53 Are you greater than our father Abraham? He died, and so did the prophets. Who do you think you are?”

54 Jesus replied, “If I glorify myself, my glory means nothing. My Father, whom you claim as your God, is the one who glorifies me. 
55 Though you do not know him, I know him. If I said I did not, I would be a liar like you, but I do know him and obey his word. 
56 Your father Abraham rejoiced at the thought of seeing my day; he saw it and was glad.”

57 “You are not yet fifty years old,” they said to him, “and you have seen Abraham!”
58 “Very truly I tell you,” Jesus answered, “before Abraham was born, I am!” 
59 At this, they picked up stones to stone him, but Jesus hid himself, slipping away from the temple grounds.

The Jewish leaders first respond to Jesus's claim that one can avoid death.  "Ha!" they say, "Even Abraham died".  But they misunderstand Jesus's meaning.  This allows Jesus to discuss Abraham further.  When the Jews sarcastically asked, have you seen Abraham, Jesus says, "Yes!"  He then goes on claim to have existed before Abraham.  But he says more than that.  When Moses, before a burning bush in the Wilderness (Exodus 3: 13-14), asked for God's name, God responded with "I am!" Jesus uses that same phrase, identifying himself with God. The Jews catch this meaning and prepare to stone him for blasphemy. But Jesus hides, then slips away.

Why must God-in-the-flesh first "hide" and then "slip away"? Why would God run?