First of all i can not even see the point that the author of the article is using to claim that zhuangzi is inconsistent, the three propositions that he uses are not mutualy exclusive, and thus there is no inconsistancy n the reasoning of zhuangzi in any way that the author points out.
Secondly reasoning or consistancy is not really a requirement of philosophy or even for knowledge.
As for the etymology of philosophy it is the etymology of the term not it's modern usage. But the daoists are indeed philosophers in that sense of the word, especially since sophos in ancient greece was more related to wisdom than knowledge. In fact the sophos in the meaning of a sage is very much inline with doaist/sage/immortal as used in daoist works.
Secondly the shortcomings of language is a main point in laozhuang philosophy and as the author was tangenting in a way yet blatantly missing, it is not to be considered an inconsitancy in thought, but rather a usage of language that requires certain metalinguistic understanding. Laozi makes use great use of antinomies while zhuangzi makes great use of allegories to make points that carry a very consistent philosophy using a language that otherwise lacks metalingusitic and metacognitive terms needed to convey the meaning of that philosophy. The touch upon subjects upon both metacognition, metaknowledge and metalingustics that western philosophers are today considering vital in modern philosophy, and thus i find it hard not to regard them as philosophical.
To say that Daoism only argues that "shit happens" and "ignorance is bliss" is total ignorance of daoist philosophy.
And the idea that developing and gaining knowledge is lesser that realising ones ignorance is a prominent idea in western philosophy as much as many other philosophical traditions, And to say that this concept or idea is not philosophical is to deny much of the success of modern western philosophy.