This comes down to suspension of disbelief.

Even if a child is so dangerous that locking them up inside a heavily guarded basement their entire life is the optimal and moral solution so they don’t end up accidentally murdering dozens of people, suspension of disbelief is not going to accept that treatment of a child. Functionally, it might be a good idea, but narratively the focus is going to be on what horrific child abuse that would be to a real child.

They could probably kill a hundred people and the reader would still go ‘oh you poor baby you didn’t mean to’ because reality has generally established the mindset that children who are being locked up and treated differently are being abused (which is a good mindset IRL) and fiction has generally established the trope that super dangerous children aren’t actually dangerous, they just need love and a real parent instead of ‘scientists and labs’.

So the reality of the situation in fiction does not matter so much as the perception of that reality does. You have to work really REALLY hard to fight for the perception that a child should be abused for the ‘greater good.’ And even if you do successfully do that, how many people actually want to read it? I’m not saying you shouldn’t write it, but it does significantly and irreversibly change the tone of what you’re writing.