1. I thought alignment capped out at 100. how did you get 150?
2, I don't believe this is due to your own personal corruption level.
In the monastery there are a bunch of greyed out options based on what route you are and what choices you made in the monetary previously.
IIRC I had this specific issue before with this specific character. Don't quite remember how I solved it, but IIRC it involved making some different choices / route in the monastery.
edit: oh derp. I fail at reading. you got over 100 corruption via save editing.
well. it might be an issue with the editing.
or maybe you edited your corruption at the wrong time. maybe you were supposed to trigger an earlier thing first using high corruption, that you failed to trigger because you raised it just before the conversation via save editing.