You can read the american militarys paper "The sun as a nonstate actor" online and while they see it as a worst case scenario for civilisation as it means data and sattelite loss besides major blackouts they seemed most worried not about the sunstorm kicking them back to the bronze age but rather that rocket systems and other hightech capabilities for warfare would be rendered useless for some time which might tempt less sophisticated powers to get uppity.
Now, I dont know how they came to zhat conclusion but they also wrote theyd need 4-10 years to rebuild infrastructure.
So while Varg has a point concerning our reliance on great amounts of hightech which shouldnt be taken for granted, his 6000year wrath of the gods cycle that reduces us to tribes permanently seems more like wishful thinking meeting dramatisation.
Hed love to see being proven right in his lifestyle after all and is a self confessed dreamer.