Well, yes, but we al know these are amongst the world’s top students and suddenly they are intellectually marooned, until this is resolved.
(Granted the ban has been stayed, we have many examples where the Trump administration has refused to act until the Supreme Court has issued judgment, and even then been dilatory. So I don’t think we know what will happen.)
Current UGs wishing to transfer to British universities for Autumn 2025 do so on an ad hoc basis, so there isn’t much concept of fairness, usually. The large majority of Harvard students are very successful there, with an A- average, so we are likely to be happy with them. I suppose if there is a huge amount of interest procedures will need to be developed.
Students part way through a two year Masters will probably stay in America and there are many excellent programmes that can absorb them. Medical and law students, ditto, for curricular alignment. Doctoral students may be in a real fix, sadly.
One hopes that the small number of British and Overseas students who may have accepted Harvard and declined their UCAS choices for this Autumn will be permitted to revisit UCAS and make Firm and Insurance choices from their offers. I should think that British universities would be happy with this arrangement, though it depends on my assumption that numbers are small.
Why is this not fair, and why would we not be enthusiastic as a country with Harvard transfers broadly speaking?