If he knew about the exculpatory evidence, as your hypothesis presumes, he could have seen it without making it public. Happens all the time.
Motion denied.
My hypothis does not entail Sullivan knowing about the nature of the evidence. I assume and it could be wrong totally, that the evidence that Sidney Powell wanted was being used in ongoing investitgations and that is why it could not be handed over, and that there must be some interla legally type message that says this to lawyers who want such evidence.
Hopefully all of this will be made clear pretty soon.