This is a pretty embarassing way to open this article:
Mars does not have a magnetosphere. Any discussion of humans ever settling the red planet can stop right there, but of course it never does. Do you have a low-cost plan for, uh, creating a gigantic active dynamo at Mars's dead core? No? Well. It's fine. I'm sure you have some other workable, sustainable plan for shielding live Mars inhabitants from deadly solar and cosmic radiation, forever. No? Huh. Well then let's discuss something else equally realistic, like your plan to build a condo complex in Middle Earth.
NASA legitimately has a plan for this, and no it's not crazy, and no it doesn't involve restarting the core of a planet:
https://phys.org/news/2017-03-nasa-magnetic-shield-mars-atmosphere.html
You just put a giant magnet in space at Mars' L1 Lagrange point (the orbital point that is stable between Mars and the sun), and then it will block the solar wind that strips Mars' atmosphere.
Otherwise cosmic rays etc are blocked and interrupted by the atmosphere, not the magnetosphere.
The confident dismissiveness of the author's tone on a subject that they are (clearly) not an expert in, let alone took the time to google, says all you really need to know about how much you should listen to them.