It's interesting as a parallel. When Zaki's DNA reports came back, he told Arzoo "when no one believed in me, you did". And now when Arzoo is saying something, Zaki immediately said it must be some mistake. I know that it seems improbable to them all, but Sahir's face when she's talking to herself later definitely says he hasn't pushed her words aside like the others.
But yeah, the point is that I really do love that Sahir's first reaction to anything Arzoo says is to believe her.