I added the zip package to a file system. As expected the zip command comes from the zip package, however unzip is still a link to the busybox executable.
unzip actually comes from the unzip package not the zip package! But you did point out that unzip is not configured for using update-alternatives, so I fixed that.
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=b85ee032233958f4bad967de469ddf16e783e6af