Because just releasing it would be tantamount to a public lynching. Regardless of guilt or innocence, anyone on that list would have their public and private lives ended. They'd lose their jobs. They'd never be able to go anywhere without that following them.
Any responsible administration would say, "that list is part of an active investigation, and we're not going to comment on it."
And then, when someone was charged, release that they were on that list. That's it.
But this denial that the list even exists now, along with Trump's little tantrum about it at a press conference is the worst way to confirm that there is a list AND Trump is on it.
