The reality is that there aren't going to be that many White South African "refugees."
It barely needs to be said, but just to get it out of the way, there is no genocide against them, they aren't rushing for the borders.
Second of all, seventy percent of White South Africans vote for the Democratic Alliance, the expressly liberal party descended from anti-apartheid parliamentary parties. Though it has it's conservative wing and it's leadership has been known to be tone deaf at times, it does reflect that most White South Africans support living within the framework of the Rainbow Nation.
Third and pursuant to the above, it's not like the DA is the only "White" party. The Freedom Front+ is the expressly right wing, Afrikaner nationalist party, tied to separatist movements, the political home of former apartheiders. Though it can't openly defend the old order, more than one of it's members has been investigated for remarks that really come close to crossing the line. And still, a super majority of White South Africans choose the DA.
Lastly, the seriously racist, yearning for apartheid types, don't want to go to America. They want to carve out the Volkstaat, an Afrikaans-speaking White ethnostate, from the territory of South Africa. It ain't gonna happen, but leaving the county fully and moving to America would still be a step in the wrong direction for them.
Which leaves the obvious question of, who is actually going to take this offer? Musk fans? The racists who'll settle for a country run by a racist if they can't make one of their own? The equivalent of economic migrants? People who've taken in too much American culture from Television and the Internet?
It's a stupid, racist plan and the results, other than showing once again that Trump is stupid and a racist, will amount to a couple lines in the history books about this nadir of American dignity.