KAU is accused of hiring well-known professors to boost university rankings by adding affiliation. Is it ethical to accept this kind of offer?
This behavior seems just as unethical as to put someone's name on a paper while he has not worked on it, and for the same reason: it provides the academic world with a wrong information about attribution, and the academic world wants to use this kind of information. Less abstractly, it means that students or scholars might be fooled into going to a university expecting to be taught by or to work alongside high-profile professors while the university really has much less to offer than it pretends.

Now, it could be argued that it is the job of the rankings to design them in a way that is not so easily played, not the job of the professors to act according to such ranking.

Also, we currently do not have clear and well-admitted ethic rules for affiliation, while we do have such rules for authorship. This makes the ethical lines much fuzzier, but in my opinion the conclusion to draw is that we should give ourselves such rules.