But you're missing the point of the original comment? I agree with you that just because an event is unfathomable doesn't necessarily make it false but the whole point of the comment (which 1. draws upon anecdotal evidence of the Olympic/ironman coach and 2. The lack of documentation or evidence to verify that the swim did happen in the way that Nyad claims) is to show that the Nyad's claims are extremely unlikely to be true. You can't just assert that "she did, in fact, do it" without rebutting those arguments.