Move on, at least for now.
Talk is cheap, and going to the Discord Channel to plead a case, when all one can bring are excuses and a "promise" not to do it again doesn't really mean anything. At least the blacklisted person must show that he or she can do better first.
For example, grow your blog. Show that you can write articles that are not plagiarized and that could add value to the community. Also, keep in mind that the Steem blockchain is a big place with a lot of DApps to explore. Why not explore those first. See how you can contribute and do your best to be a valuable member of the community. This way, when you go to appeal your case with the curators and managers at Musing.io, you can show that you really have improved, that you now know better, and that you are a valuable member of the community who can contribute and add value.
Of course, when all is said and done, there is no guarantee that a blacklisting can or will be overturned. At this point, the best thing one really do is move on. Like I said, the Steem blockchain is a pretty big place. And there are a lot of DApps to explore, enjoy, and also earn Steem with.
Hope this helps.
I think Musing.io has a discord channel and you should be able to reach out to them there and let them know you have regretted your past mistakes and actions and
you will never do such anymore,talk to them about it and they might accept your plea and decide to remove you from the blacklist....