The CPSC proposed rule restricts the sale of magnets as novelty items or desk toys. It does not restrict the underlying concept of "tiny round magnets"; if there was a high school science project that needed them, for instance, it would remain lawful to sell them for that.
Here's the specific proposed language:
any aggregation of separable, permanent magnetic objects that is a consumer product intended or marketed by the manufacturer primarily as a manipulative or construction desk toy for general entertainment, such as puzzle working, sculpture, mental stimulation, or stress relief
It's pretty much as simple as "you can't market magnets like this as novelty items", and that's it. That seems reasonable to me.
You could probably set up a business selling them as a lab supply to nerds knowing full well that 99.999% of your sales were to people using them as desk toys; as long as you aren't inducing the public into using easily ingestible rare earth magnets as desk toys, you're probably fine.