Greetings!
I think there are a couple of things going wrong with your post and some of your assumptions.
Regarding your thought that Jehovah God doesn't deal with us "directly" because we are imperfect, that is not quite accurate nor is it accurately what is taught by Jehovah's Witnesses.
Aside from a few bible notables (Moses, Abraham, Jesus), and maybe Adam, there is no scriptural evidence that Jehovah God ever "talked face to face" or directly with humans. Even these examples, are sketchy. The bible refers to God and Adam having conversations and there is the moment of God's passing his glory over a covered up Moses. And we can assume that there would be no mediator, not even angelic between Jesus and his prayers to his father. But otherwise, we usually assume that God always uses a messenger, usually an angel as a go between. Even when the scriptures refer to meetings between a man and God "face to face" or talking with Jehovah (as in the Abrahamic passages) this is referring to the person talking with God's angelic representative whether that representative is materialized or not.
Obviously, we can disprove the assertion above/presumption in your post by simply referring to a few example of God dealing ("directly" -but actually through his messenger) with imperfect sinners: 1) God dealing with Adam/Eve after their sin; 2) God dealing with Cain after he murdered Abel; 3) God empowering Samson after he sinned (many times); 4) God blessing/dealing with David after he sinned with Bathsheba, etc. etc.
(Maybe "dealing" with is a little too vague of a term for you to be using.)
The point is that God DOES deal with imperfect sinners. That he does so is the WHOLE POINT OF THE WHOLE BIBLE IN THE FIRST PLACE ISN'T IT?
If God was above dealing with imperfect sinners than he would have no connection with mankind in the first place. So your basic presumption is false.
With regard to Satan entering before God there are a couple of things to keep in mind. Being in Heaven simply means being in the spiritual realm, i.e. not within the physical universe. More specifically it refers to that part of the spiritual realm wherein God hangs out (although not being physical or having any dimension you understand I am just being metaphorical).
So to come before God in Heaven just meant essentiallly to be in (spiritual-space) proximity to God.
But there is a second aspect to being in Heaven and that is to actually receive the "light" or blessing/favour that emanates from Jehovah God to ones in heaven, the angelic host.
The Bible indicates that some of the angels, those that sinned by taking material form and having relations with the daughters of men, (and maybe others that have likewise "fallen") are existing in a state which is called "tartarus." This means that although these are in the spiritual realm they do not receive the "light" of God and so in fact they are in "darkness," again metaphorically speaking.
Thus it is not only possible but also likely that the one called Satan was also in the same state when he entered before Jehovah God as related in the book of Job and in fact has probably been in that situation since he "turned."
Witnesses believe that for a time, until 1914 to be specifici, that both Satan and these other fallen angels, also referred to as demons, could freely travel "about" the whole spirit realm, including coming into the "proximate zone" of being close to Jah (aka "Heaven"). But after Michael/Jesus' war, these ones are no longer permitted to come near Jehovah God at all, i.e. are no longer permitted into "Heaven" but in fact are now restricted to a very limited "area" of the spiritual plane which coincides with the physical location of our planet Earth.
-Eduardo
