What Sort of Man Can Kill an Emperor?

The Imperial Herald today released an article about the man allegedly responsible for the regicide of Emperor Hengist Duval.
The article detailed Brendan Paul Darius’ upbringing in Eotienses, the home system for the bulk of Patreus’ activities. His parents were a relatively wealthy client family under Senator Patreus known for their observation of traditional values. They worked on one of his many estates in the system. After completing his formal education in history and ethics he served as an officer on one of the Senator’s Majestic class Interdictors, eventually rising to the rank of captain.
Following two decades of distinguished military service he joined one of Senator Patreus’ liaison teams responsible for maintaining relationships with colony governors, planetary leaders and starport officials throughout the Senator’s region of controlled space. His dedication and talents saw him rise above his parents’ station to become patron.
The story tells of a man dedicated to service and traditional imperial values. A man who eschewed personal comforts and focused on his work. In the end the puzzle remains – why would such a loyal man kill his Emperor?