There's a lot more linguistic roots to Germanic in English than there are to Norwegian in practice, and I think you'd also find more French roots in there too. The claim being made that it's a Scandinavian language is, in context, a bit bold.
We were invaded by the Vikings in the Middle Ages, yes, but also the Danes (Denmark), the Jutes (Denmark/Germany), the Angles (so much so that Angle-land is the root form of England as a name, but also Denmark/Germany) and the Saxons (Germany) before the final invasion from the Normans.
Now there is an argument that the Normans were part descended from the Norwegians, but there was a lot of intermingling culturally (including linguistically) between the people from that far north with the folks in West Francia (modern western France), and the folks from the Gallo-Roman area (so, the Gauls, the Romans, basically a large chunk of modern middle Europe). And of course, the Roman influence before that would certainly have brought things from further east.
It's complicated because we're doing a lot of guessing about something that has a lot of cross-pollination in lots of directions. But I don't think it's as simple as 'it behaves a bit like Norwegian' which is the root of what the paper is claiming - there's roots of older languages still there.
