Jihwa has had short hair, shorter than what is common to his position as a jangban's son, from the start of the story. Also the panels showing him with short hair is backed by black, a common convention in Asian mangas for depicting scenes taking place in the past. It's more likely, Jihwa was dishonored because of sodomy, as opposed to your theory unfortunately.
SPOILER ................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
Aka the topknot incident happened prior to the kidnapping of NK.
Spoiler and Theory!
.
.
.
.
.
.
.
Just read the raws and in the first pictures jiwah has no hair knot sooo my Theorie is that SG found NK or like safed him (I hope he is safe please please pleaseeee) and after SG found out about the plan jiwah had he like dishonored him and cut his hairknot of???