He was to use them in his lawsuit against Hillary, et al. It would not have been to his advantage to make them public before any legal proceedings.
I hope his attorneys used the defense that as SOS Hillary had unsecured server/printer in a room in her house(closet) where her housekeeper use to get her papers off the printer.
Also she had a server in a bathroom closet at some IT company who had a business in an apartment loft that had no security.