A tactical retreat and running away is not the same thing. I think Orochimaru is just retreating from Naruto's barrage of attacks, maybe waiting for an opportunity to counter attack, or maybe he just wants to see just how much kyubi chakra naruto can extract. Nothing in this chapter indicates that orochimaru is afraid in the least. Quite the opposite in fact. Naruto's chakra projection had the form of a giant kyubi, and Orochimaru's just standing there, basically eye to eye with it, and probably saying "ok, you're really big...and?" Orochimaru probably has a few things he wants to accomplish now that this unexpected situation arose, and I think gathering information about Naruto's new abilities one of them, while getting his hands on yamato is another.