He sees the frown, but as he doesn't know the source of it and Blackwall has no little authority here which means Anders doesn't push his luck and ask about it.

"If one of them works, I wind up not possessed and Justice returns to the Fade where he should be. If none of them work, I'm still possessed. One of the other healers, Adelaide LeBlanc, says that we'll find something else. We'll see." The latter isn't delivered with the greatest amount of optimism. "I don't know if there will be a solution. It's not like someone being possessed is usually able to even seek anything out. But we can lay groundwork for the future, even if there's nothing to be done about Justice."