It's relevant since the system is overstretched by the amount of people arriving, which would allow for other stuff like this to slip through the net. Sweden (either immigration bureau or the government) did go out yesterday and officially statedthat they aren't show to provide housing any more and that people should stay where they are if they have housing there rather than risk not getting it here. There might have been something about not taking any more asylum applications as well (the waiting period for the asylum process is now 3 years - longer than you have the right to stay according to the new asylum policy), but I'm not 100 on if I remember that correctly.
Back to LW's article though - it should be noted that Avpixlat ("Depixled") is a notorious right wing conservative site. Furrhermore, while I didn't read the Swedish version of the article I don't think it was made clear what kinds of weapons it was, and the rural border to Norway is well known for it's large amount (relatively speaking) of illegal stashes of WW2 weapons in various states of disrepair. So I would need clarification that this stash was really owned or brought in by immigrants, and preferably by a less biased source, and not just kept there by the owner of the housing site, before I could conclude if this I'd trustworthy or not. Because because it is from Avpixlat I immediately think it's likely to be angled somehow or otherwise kit telling the whole truth.