Vanilla 1.1.9 is a product of Lussumo. More Information: Documentation, Community Support.
When I log out and try to post an answer, I don't see the community wiki checkbox. If I log in, I see it. So your hypothesis appears to be right.
My experiments also confirm that the CW checkbox doesn't appear for new users. I've asked this question on meta.SO.
It looks like you need 10 reputation to see the CW checkbox when you first ask a question. I think this is fine, since it protects new users from making a post CW before they know what that means (remember that CW is currently irreversible).
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