Establishment does not want power redistribution. Most people look to government as having a role of providing shared prosperity, instead of just forcing you into war and to go die for your King’s amibitions. A conditional welfare system is rationed by political preference, and expensive to police and administer. UBI provides the shared prosperity at a 0 effective tax rate. You’re simply transfering very high income’s taxes to lower income people in a net 0 transaction for the state. With UBI, every corrupt empire spending plan must justify taking away equal cash alternative to every citizen/resident, and so the political power of establishment/rulership representatives is redistributed to the citizenry far better than election promises meant to champion a specific constituency (necessarily at expense of all others) without the obligation to follow through and deliver. More bureaucratic allies of the empire is also a corruption, if their function is fundamentally useless and can be replaced by UBI.

UBI leads to massive economic growth because wealth always trickles up, and redistribution is just step 1 in trickling up to all workers and owners who make more to sell more to broader population that can buy more.

A better closing sentence would have been. The objection to UBI is that the establishment loves more fascist totalitarian power instead of losing that power.