I have discussed this issue so many times that it seems best to keep this treatment as brief as possible.
Traditional mysticism and Zhuangzi's mysticism are radically different; indeed, they are incompatible.
Traditional mysticism ends in content — it leads to knowing something about Reality. It can thus speak of the One, God, Universal Mind, Buddha Mind, Absolute Self, Brahman, Dao . . . whatever. This is because "enlightenment" reveals something about the way things really are. Some form of contact is made with Reality. There is something else out there and we find it. Maybe it was us all along, but still we have found that we are It, and It is something. Traditional mysticism also typically involves some form of salvation. We are delusional, live in maya, are in bondage to the karmic wheel of birth and rebirth, imprisoned in an evil body with an evil self, separated from our Source — in a word, we are lost and need to be saved.
All this might most easily be described as spiritual metaphysics; all protestations to the contrary, a great deal about the way Reality actually ‘is’ is either averred or assumed. Its basis is essentially religious belief.
Zhuangzi would have none of it. His Dao is a psychological Dao, a state of mind, and says absolutely nothing about the way things really are. The "oneness of things", the "equality of all things", the "non-discriminating Dao" — all these are expressions of a liberating point of view, not a statement about Reality. The moment they become the latter, the spell has been broken; once we 'know' something about Reality we become dependent upon what we think we know. What if we are wrong? Zhuangzi cannot be 'wrong' in this sense, because he knows nothing about the way things "really are". However they are is affirmed.
"Handing it all over to the inevitable", "hiding the world in the world", "depending on nothing", entrusting oneself to the flow of apparent reality, all these are an affirmation of what we cannot know, and the subsequent mystical experience remains empty of metaphysical content. Indeed, none of them would otherwise be possible.
Chad Hansen, it seems to me, has thrown out Zhuangzi’s unique mystical response to his skeptical conclusions because he has failed to understand how different that response is from traditional mysticism. That that form of mysticism is the default response of humanity generally (as Huxley’s Perennial Philosophy makes clear even as it advocates it), and thus became the traditional reading of Zhuangzi’s mysticism, has only further obscured his radical vision.
You can check out Scott's writings on Zhuangzi here.