In Ido, the constructed language he helped to build, Louis Couturat attempted to introduce vel, a conjunction that would express inclusive disjunction—so that, in logical sentences, the conjunction o(d) would express exclusive disjunction.
Louis Couturat was a logician who corresponded with Bertrand Russell. For some time, the conjuction vel was adopted by the Ido Academy and people started using it. However, in Progreso, the official Ido magazine, Couturat argued that Idists were using vel incorrectly. For instance, somewhere one could read: "We offer gratis [vel] not gratis books". He argued that the use of vel in that sentence is wrong, since a book cannot be gratis and not gratis at the same time. Similarly, he said that "in the daytime [vel] in the nighttime" is illogical, since day and night cannot exist at the same time. However, he gave this sentence as a "good" example: "We are looking for someone who speaks German [vel] Ido", saying that German and Ido can coexist at the same time.
So my question is: was Louis Couturat right when he implied that the inclusive disjunction must be valid for each element of a group considered individually (i.e. a single book cannot be gratis and not gratis), and not only for all elements considered as a whole (i.e. some books can be gratis while the others are not)?