Yes, means-tested welfare is different than UBI. But it's not different in a way that I see any coherent argument makes UBI more prone to being turned into a transfer from the wealthier bare-minority to the poorer bare-minority through democratic process. (Classically, that threat is an argument against democracy generally, recently it's been retooled as an argument against UBI; in both forms its a narrative appealing to the assumed ignorance and venality of the masses that doesn't seem to have much support in actual behavior of real democratic systems.)