Originally, four sect elders had been dispatched to accompany Aksai to the mysterious location protected by the grand formation.
However, only three were meant to enter the formation with him. The remaining sect elder was supposed to return to the Black Blood Demon Sect and provide Haitin with a detailed report.
The bald elder and his ally had sabotaged Haitin's plans by killing their fellow sect members. They then went ahead and got killed by Aksai.
Since the bald elder and his ally had deep connections with the Eastern Limiya Gate, Aksai wasn't entirely lying to the grand sect elder in front of him. It was just a twisting of truth to give more solid credibility to his concoction of lies.
This blend of truth and lies was something Aksai had carefully crafted even before leaving the Enchanted Everwood Farm.
Additionally, he intended for Haitin's sect to focus on the Eastern Limiya Gate, hoping they would damage its interests as a form of revenge.