Best to put this into a separate topic. I agree that Abhorath’s behaviour is a bug. My original post could be dismissed as “working as intended”, so other issues we find merit their own threads.
[edit: @Snooj has created a Bug Report for removing gems casting lycanthropy, thank you, Snooj: [Investigating] Removing Lycanthropy gems cast lycanthropy]
I’ll likely create another post about Astral Spirit (can select a lycanthropy gem, but it remains and purple gems get removed).