Interpretations of Kinstrife and taboos against killing kin

In the campaign that I am playing in my character a Humakti has just returned to his home stead after 11 years of wandering.

The stead is part of the Tresdarnii as outlined by John Hughes in his excellent Questlines articles. The stead is currently divided between two bloodlines a traditionalist orlanthi (my character's) and a yelmalio worshipping line.

On his return he has found that his half brother, who has always hated him is a Gagarthi Warlord (tacitly supported by Harvar Ironfist) who has been terrorising the local area for a number of years. The clan has outlawed this brother but refrained from attempting to kill him because of fear of reprisals by Harvar and because of taboos about killing kin.

My character has taken upon himself the task of killing his half brother.

Would my characters killing former brother still be classed as kinstrife in the light of the fact that he is a Humakti and his brother is an outlaw.

Any thoughts would be of great interest, thanks

Mark Adri-Soejoko