As far as i know, those nukes weren’t able to be deployed without the soviet codes. Soviets maintained control both of the launch sequence and operational control. At most, Ukranians could have used parts of them. At the time Ukraine disarmed they had no nuclear program in place to produce more or retrofit the existing nukes to new launch methods. They would have had to start from scratch. It also painted a target on their backs that at the time nobody could have done anything about to protect them. I cannot imagine a better outcome for Ukraine in the present had they chose to keep the non functioning nukes. Russia was going to come for them had they not given them and Ukraine was coming to terms with its own independence happening just 4 years earlier.

So yeah, disarming in this specific situation was the only choice at that time for Ukraine. You can’t just grab another country’s nukes and use them. They are made specifically so you can’t do that, so that they can be deployed in allied countries without significant danger to the manufacturing country.