God Bless You swordAnon.
Your idea is good, but it is too complicated.
How could Hunter know the repair shop would turn it over to the FBI?
Unless he knew it was a front for the FBI?
It is more likely he was drunk, brought it in and forgot it.
When discovered, that is when he thought fuck it, he is going to get screwed again as usual, so he will take the whole scheme down with him.
That is my theory and I reserve the right to just as wrong as everybody else.