Someone in r/Sweden who works in the field pointed out the severe lack of credibility of the researcher who published this finding so do your due diligence and check your sources before jumping to conclusions
To put it gently... cough Where does r/Sweden get its credibility from?
The debate in Europe is so toxic, on one side starry-eyed humanists, on the other narrow-minded losers. Each resort to separate little bubbles where they can reaffirm each other. In the middle, reasonable people get squeezed out.
As others have pointed out, the discovery reported in the post is quite reasonable, given the migratory, raiding and trade patterns between the Arab and Viking worlds in the era discussed. Settlers and converts (of tradition, religion, etc) are also common within intersections of 2 or more cultural groups interacting under any pretext. The post also outlines physical evidence, which has/will presumably be re-examined directly by other researchers to verify and extend lines of inquiry.
Some comments here like Rusanu's are annotated with useful links that you should probably read to understand how unusual the discovery actually is, instead of supporting baseless attacks on the source. It is mildly amazing to see the mental gymnastics being exhibited by some comments (including the ad hominem attack reflected in yours) in quest to refute a completely uncontroversial issue.