The minister decided to go public

It almost sounds like he did it preemptively, which he did not. According to The Local

It started with Nyhetsbyrån Järva naming him last week,

and

In fact, the only government confirmation of his identity came inadvertently when the Moderate Party’s deputy party secretary phoned up the editor-in-chief of Västerbottens-kuriren to berate him for publishing the minister’s name.

https://www.thelocal.se/20250709/why-are-swedish-media-suddenly-naming-forssell-as-minister-in-white-supremacism-scandal