Beowulf translation is a whole academic field, the translation has been debated ad nauseum for 100s of years, Tolkien had his own translation and opinion, which differed from others. One additional scholar adding his own interpretation doesn't necessarily overturn anything. There is not enough detail in this article to know how compelling the case is or what the counter arguments would be.
> There is not enough detail in this article to know how compelling the case is or what the counter arguments would be. The only real way to make the case compelling would be to discover new Old English texts. So there is enough information; the case is not going to be compelling.
The fact that earlier translators had to break up the original sentence and insert an exclamation point after "What" is already a bit suspect. Walkden's interpretation actually makes more sense, when you see examples like "Hwæt stendst þu her wælhreowa deor?", meaning "Why are you standing here, cruel beast?"
This may be a case where early translators over-indexed on e.g. Latin patterns and made a mistake which was then just accepted by subsequent translators.