Perhaps foreign enemies have made sure that list isn't released, over threat of war, financial sanctions or who knows what else.
Perhaps, releasing the list would throw so much chaos into the military, business and political class of America that it would open it up to such chaos that a foreign nation could take big chunks out of America.
Or maybe, some of the nonces are really, really, really powerful and Trump's choice was "back down and take the L or we bankrupt your country and everywhere will look like Portland".