Taking away freedom is always about "saving children's lives". It's so common in fact that the instant one hears about "saving children's lives" we can be certain something very bad is going to happen.
I am not a big fan of copyright myself, but calling being unable to use someone else's story for yourself "taking away your freedom" is a bit too much.
I mean, no? There is absolutely no indication that that particular slippery slope is being slid down. Can you even point to anyone advocating for infinite copyright on all works on the basis of the Great Ormond Street example?
The proper solution would have been for the state to fund the hospital as needed, while freeing everyone else to create content based on Peter Pan if they wished so.
Civilization is made of unsavory compromises... Funding by taxation and committee spending, or by fetishisation of conspicuous consumption are also pretty bad and yet quite prevalent.
In this case the copyright seems to have expired essentially everywhere, but a special UK extension for Peter Pan allows for royalty collection for performances or adaptations of the play there in spite of the copyright's expiry.