I'm not saying this is a valid reason to ban the sale of these items. (Sell anything, so long as you make clear warnings about non-obvious risks. Thus, a chainsaw doesn't need much warnings, because it's a chainsaw. But little magnetic balls which are very appealing to children but also dangerous - yep, give them some clear warnings.)
There has to be a point where we just throw our hands up and say the person deserves a darwin award. I don't think there has really been any epidemic concern over teenagers swallowing these though, and I don't think younger children use these as fake piercings.
I kind of agree. That's why I mentioned chainsaws. This instruction manuel for a Stihl chainsaw is, I think, good. There are many pages of warnings. Most of them are informative and address real problems - page 4 talks about why this chainsaw is a special use saw. There are no "Don't hold the wrong end" warnings here.
Some things are dangerous. Everyone can reasonably know they're dangerous, and we don't need to withdraw those items from sale. Other items are dangerous, but those dangers are not obvious, and even though we put warnings on the objects we still find people being harmed.
Again, I'm not sure that harm is enough to force some items off the market. Maybe just bigger, better, warnings.
Given your continued insistence on trying to change the argument to one about the elimination of all small round magnets, I can only assume that you're either trolling or just completely unwilling to think about other people's positions. You certainly don't come across as stupid enough for it to be anything else.
That is to say, given the rather high quality of your other contributions to the site, I can't imagine that your posts here are only accidentally coming across as obtuse. Perhaps I'm wrong! It's been known to happen.