It's a national news story thats come to light due to a large number of otherwise healthy, fairly young workers getting sick and dying from silicosis. The suggestion to ban came directly from the occupational safety watchdog, who are tasked with keeping workers safe. https://www.safeworkaustralia.gov.au/safety-topic/hazards/crystalline-silica-and-silicosis is pretty comprehensive.

In February they released a report (https://www.safeworkaustralia.gov.au/sites/default/files/2023-02/decision_ris_-_managing_the_risks_of_crystalline_silica_at_work_-_for_publication_pdf.pdf) outlining exactly what you refer to, with 6 options for governments to consider. The ban on engineered stone is the most dramatic, and uses basically the same legal framework that was used to ban asbestos in the first place.

Essentially they have been screaming at stonemasons and employees for 5 years to no avail, compliance with health and safety regulations in this area is atrocious, and no matter what laws you pass, more and more people are going to get sick and die from a preventable disease if you leave the stuff on the market.

It's only in recent years that the real dangers of silicate dust have been understood and it's being banned for essentially the same reason asbestos was - it's too hard to manage safely, and the most exposed people (workers) have to be protected. Asbestos is dangerous because it can get embedded in lung cells and not be exhaled - silicate dust is similar. Makes sense to me to put it in the same category especially if some poor bastards are dying from it.