Inducing enough magnetic flux to create dangerous eddy currents in the brain is not a problem you can get without a custom power plant and extensive cooling for the superconductors (and even then). You need a field strength around 15 teslas.
HN never fails to surprise me with comments like these that can dole out exact numbers for very niche and specific hypotheticals. How on earth do you know all of that?
Isn't it obvious? They're the Brain Frier! Not the most... refined supervillain name, I'll admit. But menacing nonetheless.
I'm not the person you're responding to, but my "strong magnets aren't lethal to people" knowledge is based (in part) on a Veritasium YouTube video[0] where they visit the "World's Strongest Magnet" and do shenanigans.