Yes, there's a reason but it's also an extreme way. Keep reading, it'l reveal why he did that! If you'd like to know why, spoilers below
.
.
.
.
.
.
.
.
.
.
Minyoung only did that to separate Cheol from his abusive family. Cheol has been the punching bag of the family, almost got killed by his brother, got sent to the hospital by both, etc. So Minyoung did the more "saner" way to separate him from the family instead of literally killing them (he didn't want Cheol to hate him so he didn't actually kill them)

Is there a reason he outed him to his father? Once I saw he did I immediately wanted to drop this but maybe there's a good reason? Hopefully? One of the only things I cant forgive </3