If you look at Apple's content guidelines[0] section 2.2 they do explicitly forbid "Encouragement of criminal activity or illegal acts" Given that treason, sedition, and advocating the overthrow of the government are illegal under 18 U.S.C[1] there's a good argument that Bannon's podcast should not be allowed.
I'm not sure what Apple's mechanism is for enforcing their guidelines but it seems the argument could be made for delisting Bannon as well.
0. https://podcasters.apple.com/support/891-content-and-subscri... 1. https://www.law.cornell.edu/uscode/text/18/part-I/chapter-11...