Instead of admiring the library that Han didn't know was there, he was instead plunged into another dangerous situation involving his friend being choked by a translucent man. It was in this moment that one could already imagine options popping in thin air as the situation became very clear to Han:
1) Attack The Ghost-Thing
2) Talk To The Translucent Man
3) Head Back to the Exit
Alas there was no time to choose another option as he found himself floating above the air. He yelped and held onto his energy saber, "Ack!" Of course the ghost noticed him the moment he stepped into the library—if anything they might have noticed him right from the very start. The Moderator didn't give any clue at all!
