Excused?

"I admit that, since the events I have to describe could have taken place in several ways, I cannot make a determination among them except on the basis of conjecture. But over and above the fact that these conjectures become reasons when they are the most probable... and the sole means that a person can have of discovering the truth...[my consequences] will not therby be conjectural, since, on the basis of the principles I have just established, no other system is conceivable that would not furnish me with the same results, and from which I could not draw the same conclusions. This will excuse me from... [many, many surprising and seemingly questionable things that I have said and will say]" (59).

During the course of my reading, I discovered Rousseau claiming things about the state of nature ("go[ing] on at such length about the supposition of that primitive condition" (58)) that often violated my "inveterate prejudices" (58) and sense of the way things are. Such bold claims would cause him to have some very difficult explaining to do later, which he would do by very questionable means (most of which I think fall under the elipses at the end of the quote above).

For example, he says that without "any need for one another, they would hardly encounter one another twice in their lives, without knowing or talking to one another" (48). He portrays an isolated, solitary version of natural man that I don't think (with my "inverterate prejudice") accurately represents the human person. Because of this early attribute, he has later trouble about with how language arises, since no knowledge or mental ability comes about without necessity (48). He eventually sidesteps a full solution to this "thorny problem" which occupies philosophers "for whole centuries without interruption" (49) so that he can "inquire how they might have begun to be established" (49). How can he pull such a move? I believe this and other claims and subsequent arguments of his fall in the excused elipses, specifically under "the way in which the lapse of time compensates for the slight probability of events" (59), or one of the other objections that he lists.

Therefore, my question is: how is Rousseau excused? He seems to think that he is excused because he tried his best and because he said so (when he set his first principles, which "should not be taken for historical truths, but only for hypothetical and conditional reasonings, better suited to shedding light on the nature of things than on pointing out their true origin" (38-39) --how can you know nature without origin?). Also, perhaps his system is fine but the "results" and "conclusions" that he is aiming for are off. Thus, my question contains many questions, but generally it is about his excuse statement at the end. Do we think he is excused, and can you help me understand how? Perhaps he didn't have time to treat all of those objections, and so he shot for a general pardon?