Someone who has done nothing wrong has nothing to be ashamed of, and Paul certainly fits that description. Were the people he offended not in power, it is unlikely that Felix would have ever heard this trial. As it was, that’s exactly who he offended. Paul told the story the same way he has done over and over: he follows the law, but he also follows the Way (an early expression of Christianity). He doesn’t back down because he has been shown a far better way than the powers can ever provide.