I do not know where you are getting this from. The inventarisation and storage of the Brika finds are something of a mess. As an earlier paper published by Anne Kjelström (one of the authors) remarks:
"The problem at Birka arises from the management of the material; the contexts of some of the finds have become mixed up. Around eleven hundred graves have been excavated at Birka (or the island of Björkö); approximately half of these were inhumations, including both rich chamber graves as well as modest coffin burials (Gräslund 1980, 4-5). Most of the graves were excavated in the 19th century by Hjalmar Stolpe (Arbman 1943). During the present analysis, it became clear that the osseous material and the contextual information given on the box or bag did not always match the data published by Arbman (Kjellström 2012); there are bags of bones tagged with grave numbers that do not exist elsewhere. In other cases, there are unburnt bones in bags from graves documented and registered according to Arbman as “cremations” and bags which include the bones of several individuals while being documented as the grave of one person."
In fact, she also refers to Bj 581:
"Another interesting (and possibly controversial) find was a grave where the preserved bones do fit the original nineteenth century drawings and descriptions. This is a chamber grave furnished with fine armour and sacrificed horses. Nevertheless, three different osteological examinations all found that the individual was a woman. Whether these are not the correct bones for this grave or whether it opens up reinterpretations of weapon graves in Birka, it is too early to say." [Italics mine]
Note that the attribution is not because of marked bones attributed to a specific grave (as you claim), but because "the preserved bones do fit the original nineteenth century drawings and descriptions." She herself remains in doubt whether this attribution is correct, and concludes:
"Although not all Birka graves suffer from this uncertainty, it was decided not to associate the skeletons to specific graves. Instead, the skeletal collection is dealt with simply as “the people buried at Birka.”
Kjellström A. ’People in transition: Life in the Malaren Vallye from an Osteological Perspectve’. In V. Turner (Ed.), Shetland and the Viking World. Papers from the Proceedings of the 17th Viking Congress 2013 (pp. 197-202). Lerwick: Shetland Amenity Trust, 2016.
None of this uncertainty appears in the article "A female Viking warrior confirmed by genomics." But as the authors have to admit, the bag with the skeleton contained an extra femur!!. Ignoring completely the problem how it got there, they just excluded it from their examination. [Edit: Apparently, therefore, one of "the bags which include the bones of several individuals while being documented as the grave of one person."]
By the way: Stolpe's old notes have been accessible on the internet for some time.
Even assuming the identification would be correct, archaeologists and historians, as I have pointed out before, have moved away from the idea weapon=warrior. And you yourself admit, women burials with weapons are in any case extremely rare. To draw from these rare phenomenons wide-ranging conclusions about Viking society is building on sand. One would not draw such conclusions from Boadicea or Joan of Arc either.