Here is a possible motive:

“O you who have believed, fight those adjacent to you of the disbelievers and let them find in you harshness.” (Qur’an 9:123)

But of course Swedish authorities, like authorities all over the West, know that such passages of the Qur’an never, ever incite Muslims to commit acts of violence against Infidels. Only the greasiest of Islamophobes would ever dare think otherwise.

“Sweden: Military-aged Somali migrant arrested for assaulting 21 people,” by Arthur Lyons, Voice of Europe, September 22, 2019: