I had things out of sequence as well but I had had the scene where we were out and about exploring and he confesses his vampirism to which I responded 'Yes of course' like it was the most natural thing in the world.
So the scene with the Gur fitted into that well enough
Even though the game apparently forgot I already knew and I had the entire bite scene including the rather silly revelation that he was a vampire (as if the marks on his neck, his pallor, the dead exsanguinated boar and his confession wern't enough) later that night.
Clearly my Tav needs things in triplicate before she believes them.
But anyway, silly season stuff aside, game sometimes has missing dialogue flags or mixed up ones, and that can cause weird things like your Astarion being able to murder the Gur and there being no apparent repurcussions to it.
