Not all opinions must be taken on authority, they can be assessed on their internal coherence. The views he is putting forth are coherent and he has cited sources in a very precise manner. We can infer that he knows what he is talking about (spoiler: he does, as these are the same ideas I was referring to in my original comment).
Huh? It seems like i have showed up your ignorance on this subject and hence you are just trying to "appeal to authority" which is funny given that you have actually not mentioned any one Authority nor any papers/books in support of your argument.
I have studied Linguistics from the pov of Philosophy which any intelligent person should be able to infer from my references.
I don't think you even understand what the phrase "All languages are equally expressive" means. It means very different things when applied to Natural Languages vs. Formal Languages. The latter is where this expression is usually used/studied which is what you are parroting without any understanding.