Rest assured, I couldn't even unlock.
I do not know whether it is a bug or a specification, but it seems that ZANE can not be unlocked even if you clear the current CO-OP (cooperation) mode 4.
After i completed some missions, i got Zane. solved.https://community.callofduty.com/t5/Modern-Warfare-Forum/How-do-i-unlock-Zane-operator/m-p/11215342
However, the above is a quote from the forum, "After the completion of some missions, I was able to get ZANE."Resolved" and self-resolved question, so it is a bug, not a specification, it may be unlocked at some time.
If it is a bug, I feel that it is likely to be fixed in the patch sooner or later, but if it becomes four CO-OP mode clear again, it is too painful (Noh').
It's fixed in 1.05, but my (PC version) is still version 1.04.0.7215515
Postscript, version 1.04.0.7215515 After i clearing all (four) again, IT Was unlocked ZANE.