He got to know a famous writer who knew much more knowledge than his own (knowledge was).
为什么than从句是his knowledge was,而不是than he does?
这里不是对知道这个事情进行比较,而是对知识的多少进行比较,可以把than看成作表语,举个例子吧,你看看是不是用does?
He got to know a famous writer who knew a guy more handsome than he was.还原到原句He got to know a famous writer who knew a more handsome guy than he was.