The underlying evidence in this case is clearly fragmentary and unclear. When doing historical research, one should always be wary of finding precisely what one is looking for. Any definite statements about these items will require more research, more analysis, and most of all more data.
That said, the idea that Vikings of this era would possess important items with Arabic lettering on them should by no means be seen as a surprising discovery. The Vikings and Arabs of this period were engaged in a truly staggering amount of travel and trade, and the southernmost parts of the Viking area overlapped with the northernmost parts of Arab expansion--particularly in places like Sicily.
For just one hint of the kind of intermixing that was going on, I would recommend skimming the "Viking Age" section of the Wikipedia page on the history of Sicily:
I think it's a shame that this story hasn't gotten more attention.
True, it doesn't tell us as much about the nature of the universe as the discovery of the Higgs boson, and it doesn't represent a major advance in engineering like gravitational wave detection. But it is the only chance we have ever had to directly view a largeish piece of another solar system, just millions of miles away. The next time probably won't come until we send a probe to Proxima Centauri.
To me, the thought of an asteroid being hurled out of the solar system that created it, then traveling through the cold void for millions or possibly billions of years, and then whipping around the sun (a mere 0.25 AU distant) is just the most incredible thing. The whole world should be having parties in its honor, to wish it well as it leaves us behind. (Instead of just fighting each other over nothing, as we usually do.)