Funny i just tried to find out. ( Love it though)
Origin Behind the Mio's Nickname "The Butcher"?

Did a little more research and after reading this author bio (link below) I'm thinking this may be why? Looks like the first few courses he published on Chessable were all titled "Butcher the... " ("Butcher the Sicilian," "Butcher 1...e5: The Bishop's Opening," "Butcher the Scandinavian").
https://www.chessable.com/author/MiodragPerunovic/
I was interested in finding why Miodrag Perunović's (@TheButcher) nickname is "The Butcher" but came up empty-handed. Anyone know?