Not idolizing someone is not the same that criticizing them, of course.
I am not a naysayer to Diana Nyad, but I don't look at her as someone who has something I aspire to. It does seem like she is doing all this to fulfill some unsatisfied emotional needs, and that's not something I would ever criticize, but I aspire to deal with whatever obstacles I may have and live more intelligently. I may admire her determination and strength, but I do think they are not redirected to the things that maybe could help her live a better, happier life. Of course it's just my perception of her. But if she makes it or not, I wouldn't consider her a role model just because of that "sucess".
Well, about Terry and yoga, I think that Terry deciding to go deeper in his practice of yoga wouldn't mean that he would change his approach to swimming. Swimming is swimming, yoga is yoga - while I think TI is indeed a swimming method that requires and stimulates a practice that trains and educates your mind in a similar way to the mental practice of yoga, it doesn't mean that Total Immersion swimming is a "type" of yoga. Terry going deeper in his yoga practice would probably give him more clarity in all aspects of his life, including his swimming and swim-coaching life. But I don't think he would start his swimming practices with an invocation to Patanjali...