First, your title question is broken English. You do not “know” knowledge, you “have” knowledge (as you indeed correctly phrased it in the body of your post). You “know” THINGS. Knowing things is what constitutes HAVING knowledge.

Anywho, your title question reminds me of a recent other post in which the OP is asking about prejudicial questions:

Is there a name/term for phrasing something such that to disagree implicates yourself?

So, my point is that your question is of that nature, reeking of the presupposition that such withholding is improper. However, it may well be proper, from the concept of trade-secrets to the military concept of “need-to-know”. So, in other words, I do not agree that the term for such a person must necessarily be one having a “negative connotation”. As Flannery O’Connor once said (through one of her characters), you have to have certain things in order to understand certain things. Let’s see how YOU would behave if you somehow came upon a significant piece of information, say, a great stock pick. Information, to be useful, must often be kept secret and acted on in secret. Would you blab the stock tip, or would you just discreetly make the stock purchase?

Anyway, “closed-mouth” (to echo Gnawme, slightly edited) or “holding his cards close to his vest” perhaps are non-prejudicial adjectives describing this phenomenon.

(Again, a “closely-held” company is a common phenomenon. If you ask them how they became so successful, they will of course brush you off with some platitude like “by hard work and good management”.)

First, your title question is broken English. You do not “know” knowledge, you “have” knowledge (as you indeed correctly phrased it in the body of your post). You “know” THINGS. Knowing things is what constitutes HAVING knowledge.

Anywho, your title question reminds me of a recent other post in which the OP is asking about prejudicial questions:

Is there a name/term for phrasing something such that to disagree implicates yourself?

So, my point is that your question is of that nature, reeking of the presupposition that such withholding is improper. However, it may well be proper, from the concept of trade-secrets to the military concept of “need-to-know”. So, in other words, I do not agree that the term for such a person must necessarily be one having a “negative connotation”. As Flannery O’Connor once said (through one of her characters), you have to have certain things in order to understand certain things. Let’s see how YOU would behave if you somehow came upon a significant piece of information, say, a great stock pick. Information, to be useful, must often be kept secret and acted on in secret. Would you blab the stock tip, or would you just discreetly make the stock purchase?

Anyway, “closed-mouth” (to echo Gnawme, slightly edited) or “holding his cards close to his vest” perhaps are non-prejudicial adjectives describing this phenomenon.

(Again, a “closely-held” company is a common phenomenon. If you ask them how they became so successful, they will of course brush you off with some platitude like “by hard work and good management”.)