What the page says "doesn't contradict" does indeed contradict, if we add two additional and widely accepted premises. First: if a true existentially quantified statement about Xs can be made, there are Xs in the territory. So for example, if the airplane mechanic says "there is at least one cracked wing on this airplane" and that is true, then there is at least one airplane wing. There are airplane wings - in the territory. Second, if a term refers, we can make true affirmative statements with it. If "airplane wing" refers to a complex of quarks and electrons, then it refers. This is all pretty mundane Tarski-esque stuff.