The sequel script confirms that this character was secretly a shapeshifter, Scytale, who plays a significant part in Dune Messiah, the Frank Herbert novel that Dune 2 was going to be based on.
The aforementioned Scytale is a member of the Tleilaxu, also known as the Bene Tleilax, a group of genetically modified humans. The Tleilaxu are introduced as antagonists in Dune Messiah ...