In Act III, scene 2, why may the establishment of Claudius's guilt be considered the crisis of the revenge plot?

The crisis of a drama usually proceeds and leads to the
climax.  In Shakespeare's Hamlet, the proof that Claudius is guilty
leads to Hamlet's decision to not kill Claudius while he's at prayer--and that is the
climax of the play.

Hamlet, until he sees Claudius's
reaction to the "play within the play," isn't entirely sure Claudius is guilty.  He has
no real proof--only the word of a ghost, who, he says in Act 2.2.565-572, could be a
devil trying to deceive him (as, by the way, the witches do to Macbeth in his play of
the same name).  Hamlet needs proof.  He is too reasonable to act like Fortinbras or
Laertes and just jump into revenge without thinking it
through.

The king's reaction to the murder scene in the
play gives Hamlet the proof he needs, though, and he sets off to kill the king.  He gets
an opportunity but decides not to take it.  Why?  Because he thinks Claudius is
confessing (he isn't, but Hamlet doesn't know that), and killing him immediately after
he confesses his sins would send Claudius straight to heaven.  And Hamlet doesn't want
to send Claudius to heaven, not when his father is suffering in a purgatory-like state,
and when Hamlet might be sent to hell because he kills
Claudius. 

The problem is, though, that when Hamlet decides
not to kill Claudius because he doesn't want to contribute to his salvation, he is
playing God.  Salvation is God's business, not Hamlet's.  Hamlet is messing where he
shouldn't be messing.

The result--you see it in Act 5:  the
sight Fortinbras says doesn't belong in a castle, only on a battlefield.  Death
everywhere. 

When Hamlet walks away from his rightful
revenge, by playing God, he dooms himself and so many others.  This is the climax. 
His receiving proof of Claudius's death could be considered the crisis, and Hamlet's
refusal to kill Claudius while the king's at prayer is the climax.  One leads to the
other.