I don't see how this, "...does the exact opposite," of what Docker does—both are very different approaches to the similar goals of having individual processes run in isolated ways. Docker does it by isolating individual running Linux processes under a single kernel, whereas unikernel-based systems do it by building those processes as lightweight programs that get compiled to their own kernel images and then running those on a hypervisor to achieve isolation.
Yes, you are right, this is not a binary classification and it really depends on the perspective. What I was trying to say is that - on some levels - the two approaches are almost antithetical.
