He couldn't talk to Maerwald for obvious reasons. I talked to him later, but didn't get any relevant dialogue options. Now I've finished more than half of Defiance Bay and he still isn't talking. Was there a conversation prompt in a specific place that I missed or does it just take so long?

After dealing with Maerwald, I got that speech bubble notification on his avatar and he talked about it. I think it triggered after I was in the keep's courtyard.

Thank you. I returned to Caed Nua and the prompt appeared. I must have missed it the first time, but it's strange that I couldn't talk about it outside that location.