Due to the Sublimator's excessively powerful vitality, even with his head cleaved open by Ian's sword, Idma still had not died.
And once Ian removed the Attached Brain, the Director's eyes, once shrewd and lively, became clouded and dull.
It wasn't to say that all of Idma's wisdom was granted by the Attached Brain—he was indeed a smart man, and his knowledge justified his position. However, the long-term existence of the Attached Brain allowed Idma, a First-Level Sublimator, to prematurely coalesce a soul, and it became part of Idma's soul.
When Ian removed the Attached Brain just now, he also shattered Idma's soul, forcing him to experience the agony of 'soul-shattering' with only his own flesh and blood, using his already fractured brain.
"This is what you brought upon yourself, scum."
