I was thinking that to. If the arms are restrained and held against the chest they wold look like that. Also, we've seen them use no-name women in their rune gathering. Even if this IS a woman, there is no guarantee it's Saki.
Also when they say, "kamitsuki exposed" I'm thinking it's not Saki, but it's Haruto and his group are going to reveal themselves. They are the one's who call themselves that. Cain and his group don't even know or use the term. Also, L-elf isn't in any condition to stop Haruto from being stupid right now. I think Haruto has gained enough bravado to try to reveal himself, especially after his talk with Lise. However, he's naive if he thinks that everyone in Neo Jior, much less the world is going to accept him or the others.