There was no deus ex development in the arc, apart from Kirito saving Yui's data but that was a artificially created because of the way the producers choose to portray the scene (they should have shown it as a very intuitive simple and quick task... not as hacking the 3rd lvl Matrix). Yui's lack of cursor was a huge clue and the first one the anime gives. Yui said she "remembered" being what she was when she entered the room with the terminal.
As for poor writing, they didn't say much about Sinker guy. Presented as an expendable device in the anime. You are left to imagine how is he going to handle the Army now.