Um, a private tracker for torrent would require the user to log in. If Epic ran the tracker, it would function the same as Github and the Launcher do now, with the added benefit of BitTorrent’s ability to “fix” bad download spots with a tiny chunk, rather than downloading the whole file again.
Which is mute, as the Launcher itself could function as a private namespace distributed tracker. Wow does this with their launcher and have for the last six years that I know of. This would have prevented me from downloading 7.7gb of the Kite Demo several times today, thanks to one file always failing.
Epic could add an option to turn off sharing, just as WOW does, for corporate situations, and those that have low bandwitdh, though they get filtered out of the network by the correct algorithm anyway.