Personally I see Galt as something of a disproof-by-overextension of some of Rand's ideas. Galt was her "perfect man". For a character to be human, the author must be able to get inside their head. For even Ayn Rand herself to be unable to thus think like Galt indicates to me that she was unable to make her own thoughts follow her own ideals. As any Rand follower will agree, the quickest way to get your thoughts to stall and boggle is to try and deny a natural axiom, or push through a contradiction. (Similarly you get much the same stall-and-boggle leading to an authorial 3rd person stance, when other erroneous ideas are tried to destruction - compare most utopian fiction.) So that's a strong warning signal.

What could be the fault she ran into? I think she had a bit of the "chasing words" disease. The words for her were "rational", "mind", "self-interest" - and those are words that break down quite quickly and thoroughly when you look at the brain and the human organism in context. (In her defense, she was writing some 50 years before the science would become any good.)