The South Africa travel ban may be pointless without more general restrictions, since Omicron has now been spotted in many other countries; SA was just the first place to report it. Experts are divided on this question:
Israel is banning foreigners from entering the country and Morocco stopped all incoming international air travel. Scores of countries in Europe, North America, Africa and beyond restricted flights from southern Africa.
Given the recent rapid rise in COVID-19 in South Africa, restricting travel from the region is “prudent” and would buy authorities more time, said Neil Ferguson, an infectious diseases expert at Imperial College London.
But WHO noted that such restrictions are often limited in their effect and urged countries to keep borders open.
South Africa’s government said the country was being treated unfairly because it has advanced genomic sequencing and could detect the variant quicker and asked other countries to reconsider the travel bans.
That said, Biden was acting on the advice of medical experts -- while Trump consistently went against that advice (and attempted to get his most informed experts fired) and frequently against common sense.
...and given the number of other countries doing the same thing, I don't see how it makes sense to claim this as some foible of Biden's, even if it turns out to be unnecessary or (on the other end of the spectrum) too narrow to be effective.