That's an excellent Idea. but the first should not be there. a user shouldn't have setting for posters that specifies whether the user wants this muting to potentially take place on his posts. It should be readers or curators decide are the comments are abusive or spamming. the second point is excellent and even it can modified as

give muting option to readers not content creators.

But still people create bots to mute the comments on their posts :(