Yes, I agree that the length of the key and the real randomness are the most important points and that when those are fulfilled the recipe has sense. Neither explicit length minimality nor real randomness of the key were mentioned but the SHA advice was explicit to the 256 bits.

EDIT: To make it clearer: "Long" is not explicit. 256 bits is. The difference between real randomness and for example output of RND in your favourite language is also nowhere to be seen. Moreover the use of the "key" is dubious as it's not an encryption key at all.