That report doesn't do anything, so who cares?
i am not sure when it they changed it.. but yes.. muting in-game does "NOT" put people on your ban list.. you can do it in the after game lobby or completely manually type it in if you forget to add them to the list later.
i review old bans to make room for new ones.. if they are still within my elo i keep them banned.. if i have passed them and they are no longer going to be seen in my life.. i give them a free pass and unban them