Pure political theater that will not change the law on pornography due to precedents already set. Politicians have often used the idea of banning pornography as a way to gain attention, even though the issue was largely resolved by the late 1960s. George W. Bush reportedly considered pushing for a ban but shifted focus to national security after the 9/11 attacks in NYC in 2001.
Now, Trump might revisit this issue to gain political support and distract from his criminal and civil troubles. Banning pornography is an easy political stance to take because it appeals to both feminists and the Christian right. Even those who consume pornography are unlikely to publicly defend it, making it a low-risk issue for politicians.
The U.S. Constitution, through the First Amendment, protects freedoms of speech and expression, including legal adult pornography, as long as it doesn’t meet the legal definition of obscenity. The argument against pornography is politically expedient for gaining points with the public.