Yet you then say
the two week shut down is a **** waste of time
That is your opinion but what's interesting is then you go on to recommend, basically, a "shut down", whether you want to call it such or not.
would give him a few days of letting him settle in.
would keep him separate from your child for a few days
take him out for long and frequent walks to help him with his stress,
the "two week shut down". Maybe two weeks is longer than you have in mind but that transition time is usually necessary to avoid things like what have already occurred.
Done properly, the dog is merely crated instead of let wander around which will accomplish all the above. The dog, in between crating, is taken out, walked (alone), let play in the yard, etc. (with a leash on which is a great idea anyway).
Dogs should never be brought straight from a shelter and then have all these things thrown at them.
They don't know who you are, and you don't know how they'll react to different situations.
The "two week shut down" is to give them a sense of 1) how your home works, 2) your relation with your family and other pets in the home, and 3) that you are indeed the leader and that will lead to 4) a trust and faith in you so when things start going weird (family comes over) they look to you for guidance.
Right now this dog has no idea who is good, bad, who should be let in the house, etc.
The two week shut down will give him that groundwork necessary to become a member of your household and not become a neurotic basket case as he is already now.
That he's already failed so miserably only serves to further justify and solidify the fact he needs the shut down.