Language and thought: the case of duty

In yesterday's post, I discussed Michel Angot's claim that Sanskrit thinkers lacked the notion of "having", of "ought" and so on. In an interesting comment, Michael Reidy referred to the Sapir-Whorf hypothesis (in short: language influences the way one thinks).
In fact, Angot seems to claim the opposite. According to him (if I am understanding him correctly), language is not inseparably connected with thought but, if thought were refined enough, it would eventually influence language. Therefore (I am using one of Angot's examples): the absence of the verb "to sacrifice" does not mean (vs. Sapir-Whorf) that one cannot have the concept of sacrifice. But, if one has it, one will sooner or later "create" a suitable verb (for instance, bending the meaning of "to verse" until it can mean "to sacrifice").
Since Sanskrit thinkers did not create a verb "ought", this means, according to Angot, that they lacked the corresponding concept. Now, this claim seems to imply several fallacies:

1. 1. Why should the concept of "ought" be expressed by a separate verb? It is the case in French and in many other languages, but it is not the case in Latin, Greek and many others. Could we seriously claim that Western Christian writers using Latin as their medium lacked the concept of "ought" just because they expressed it with a gerundive?
2. 2. For instance, Kant (who surely cannot be suspected not to have had the concept of an interior "ought") wrote in German and in Latin. A reader of his Latin works (including the letters he sent throughout his life) might maintain that since he did not create a separate verb in Latin, he lacked the concept.
3. 3. More fundamentally, how do we know that the Sanskrit thinkers using gerundives did not mean to use it in order to express what M. Angot calls a devoir (duty)? If Angot accepts a shift of meaning in the usage of hū- and yaj-, why not in optative mode and suffixes? One could reply that we do see that yaj- means "to sacrifice" and we do see that mayā kartavyam does not mean "I must do". But is it really the case? Is not our interpretation of such optative suffixes too dependent on our general understanding of how Indian authors conceived duty?
4. 4. Angot seems to imply that the Western world has always known the concept of an interior duty, a duty which is not ordered from without, but rather felt as one's own. Is this really the case? One is inclined to think at Kant's Sollen and to Augustin's veritas habitat in interiore hominis. Yet, Augustin's veritas is elsewehere equated to Christ himself. And Kant's categoric imperative is not utterly dependent on each individual, since it is the same for the whole human kind. It is a low and not a norm. Is it, hence, really so different than the impersonal law telling one to do X or to refrain from doing Y (call it God or dharma)?