All aosp/cm roms are unknoxed. That has nothing to do with the bootloader. Once an S4 has been upgraded to MJA or newer software you have the knox enabled bootloader and the only way not to trip the knox warranty flag is not to root it. This flag is pretty useless and means nothing to most users. It has no affect on your phone usage or modding ability. All it does is let Samsung know that you rooted the phone if you send it in to them for warranty work. They may or may not choose to work on your phone under warranty. It doesn't affect your ability to go to Sprint and have them fix your phone. It only matters if you are going to ship your phone to Samsung to fix. If you have insurance (TEP), best buy, square trade, or any other program than you are good, Just use your damn phone and enjoy it!
Phones & Tablets: Galaxy S4, Galaxy Note 8", Evo 4g LTE, Evo 3D, Acer Iconia A500, Samsung Galaxy Tab 2 10.1, Ipad 2, Nabi 2,
Rom: Rooted Stock Odexed, Hotspot Mod, Xposed, Wanum