Given the "gift in one hand, gun in the other" history of western actions in Kenya and other African countries over the last centuries, it's hardly surprising there's going to be the random pocket of paranoid skepticism, no matter how good the UBI marketing/education. I'm personally confused as to why anyone would think it's a good idea to trial UBI in Kenya, as a sort of private charity initiative, given the sordid…
It seems to me that in this case a randomised controlled trial (RCT) would be an ideal way to determine who is right: A third of people get free money, a third of people get stay-in-school money, and a third of people get nothing. Then see which treatment, if any, is more effective at increasing the standard of living.
But you seem quite certain that data from such an experiment would not be meaningful. What kind of problems do you think would prevent an RCT from producing an accurate answer? Could we avoid these problems by instead running the trail in, say, South East Asia, or are RCTs doomed to produce unreliable data?