Atticus' words could indeed have a psychological impact on Eren. Perhaps not the one that he's hoping for, but beggars surely can't be choosers in Penance.

He turns to look at the unassuming young man who has approached him, considering him inscrutably a moment. He is surely more than he appears to be; otherwise, why would he be here?

"Why decide at all?" he replies. The vials laid out before him remain untouched.