I am not sure where you got that the propaganda and imprisonment of Orpheus was because of his mother. Orpheus rebelled against the original Vlaakith, when he learned that she might have betrayed Gith. He was defeated by that Vlaakith and imprisoned in the prism, because he has inherited Gith's powers and Vlaakith did not want to loose that in case the illithid empire returned. He was rebranded as a traitor because Vlaakith's official story was that Gith named her the ruler, and she didn't want anyone to question that.
