Answering Crowley hadn't been an option for Castiel so Raphael's timing wasn't all that much of a bother to him. He looked from the archangel and back to the demon before taking the paper with the ritual words on it and fleeing.
Crowley could stay and deal with his brother's anger. He had a soul to get out of Purgatory. Listening to Raphael be angry and then kill him wasn't something that could be done. After all, it wouldn't take long to open the door. He could use the rest of the blood - and the real stuff to do it.