There are so many things that need justification for safety reasons. All the 18+ stuff comes to mind, most notably slot machines.
Even in a free society.
Yeah and horses trampled over kids all the time. Justification enough is that the kids should've known better
"free" like in the "regulations are harmful" way?
"free" like not guilty until proven otherwise
More of a "free" like in "you are free to behave immorally"
That principle exists in a domain where you've already been alleged of wrongdoing established by a given set of laws, it just means the allegation isn't also the warrant for guilt, as in a witch trial. It wasn't meant to hand-waive away any kind of collective speculative concern
The open letter cites plenty of sources explaining why the product would be harmful to children. Convictions are made on less evidence than this.