Time-travel violates freewill because if you do something, then me going back in time to change things, the butterfly effect, it can change what you did and split the timeline so to speak. Well, I'm not saying my argument here is perfect in that it's not like all humans have absolute omnipotent free will like everywhere, like omnipresent like, like all the time and everything else, since we are not God, meaning it is not like we have that type of free will. So, a counter could say a slight violation of free will in the time-travel department may not necessarily be anything new since free will seems to be violated at times or in some ways or in other ways and avenues and to different degrees which is true which raises the question of where the line might be drawn for where free will shall not be violated from the perspective of God and time-travel and things at that level or things beyond our control.