you guys also forget that ichigo's sword was changed just by his spiritual powers in the beginning. it was much bigger than when rukia gave it to him. it is stated it was like that because the swords size/look is determined by how much spirit power is ran through it. ichigo had no control of his power so a lot flowed through the sword changing its appearance. it wasn't a full release because he didn't know the name of his sword, but it was changed nonetheless. kempachi's sword is therefore similar in that fact. he also can't control all his spiritual power so enough of his power may constantly flow through his sword making it in a heightened state but not a released state.