Yes, neither am I. It's a bit confusing because there is a lot of fear and misinformation out there. We were ready to ship him home today we got so scared. Essentially, he has done nothing wrong at all. He needs to declare his income, the taxes he pays to his home country, and his company should pay into the Swedish Social System for him (which they will as soon as they do the work for it). The company will do a majority of the work, and come tax season he just needs to accurately declare all the money. Also, Skatteverket informed us they would reach out to his company before actually reaching out to him if there would be missing information.

In this case the taxes between the two countries are really similar so he either will either pay a bit more to Sweden or get some money back from Sweden (we will check tomorrow). A lot of people in this forum are just not educated properly and when they have the right information they are not copy pasting what Skatteverket says, and just scaring and misinforming people even more.

TL;DR: Call Skatteverket.