The effect of “When your opponent would Special Summon a monster(s) (Quick Effect): You can return this card to the hand; negate the Special Summon, and if you do, banish that monster(s)” would not meet its activation requirements in the replay sent because the UCT was summoned from the effect of another card, the summon itself did not start a chain so the “when” condition was not met. If for example you retry the same situation and have your opponent link summon, synchro summon, summon cyber dragon, or summon a monster in a way that does start the chain you would be able to activate it then. For similar use case scenarios look at which cards solemn judgement can negate the summon of.