"Employing frankness in my study of natural philosophy, I would prefer to proclaim in oracular fashion what is beneficial to men, even if no one is going to understand, rather than to assent to [common] opinions and so enjoy the constant praise which comes from the many." - Inwood and Gerson
"Speaking freely in my study of what is natural, I prefer to prophesize about what is good for all people, even if no one will understand me, rather than to accept common opinions and thereby reap the showers of praise that fall so freely from the great mass of men." - St. Andre
I would interpret this as saying that Epicurus was saying a lot more than just "pleasure" is a natural guide. And I think "oracular fashion" means he was being very specific about what is beneficial and good.