He doesn't have a choice. He is being asked about it constantly in every MSM interview. His comments are being distorted and exaggerated. He either responds in kind or passively allow them to stick. He has the big megaphone, so use it.
Yes, Trump is pretty much stuck with answering that question (re Megyn) but there are ways he could do it better. He could blow it off... like... look, she asked unfair questions and I reacted but that’s old news now and I just hope she’ll be more fair in the future and possibly she’s learned her lesson.’