It's hard to blame Baez for what you blame Baez for, without knowing anything about the nature of communications between Baez and Casey. Casey might be insisting that she is innocent of everything, without wavering. Baez would then have to defend her on that basis.
I see Baez in the press every day and hear what he says. In my opinion, he is no brilliant criminal defence lawyer.
Casey has a Constitutional Right to insist that she is wholly innocent of every charge, and has a Constitutional Right to a trial. Otherwise, every government accusation against a citizen would essentially be the equivalent of a conviction if a defendant were obligated to confess to every charge. It wouldn't be much fun existing in that kind of society.
Of course she does. But good lawyering is about getting the best result you can for your client, and giving them sound advice re their prospects of success at trial. IMO, he is not experienced enough, nor does he understand things like DNA well enough to be giving her thorough and reliable advice. I see how he conducts himself in front of the press, and his unprofessionalism, lack of knowledge, lying etc...and I conclude he's not much of a lawyer. That is my opinion.
If every criminal fessed up to their crimes, we wouldn't need any lawyers, or prosecutors, or judges, or criminal courts, I guess.