It’s worth the fight, to the Supreme Court it need be, for Trump to refuse to talk to Mueller, but agree to answer written questions with written answers. That way, Trump and his lawyers can do their damnedest to make sure that they avoid any perjury-trap land mines, because I think it’s correct that Mueller would most likely try to catch Trump in a perjury snare, and as well all know from both Trumps own prior experiences of testifying, where he likes to shoot from the lip, so to speak, expatiate, and defend himself, and as we should all know from our own experiences of getting tripped up by others when in conversation, answering questions orally is most likely going to cause Trump to say something that will technically fit a very narrow definition of perjury.
Trump and his team should fight for written answers to written questions, or nothing at all.