Hi JH - with Ibn Fadlan's Risala you have got to be very, very careful, something that the writer of the wiki article wasn't.
For a start there is huge controversy regarding the translation of his "Risala" (his account of a trade emissary trip to the King of the Bulgars in which he partook in the 10th century). About the only thing that everyone is agreed on is that the Lewicki translation on which most of the further supposition is based is incredibly bad. Arabic and French scholars are unanimous that Lewicki cannot have had much respect for the original Arabic syntaxes, semantics and vocabulary, not surprising since Lewicki did not understand Arabic by his own admission and used unidentified translators to "help" him. Furthermore he was writing in French, his second language (he was Polish) with a view to book sales and much had to be re-written by his French publishers. His book was a best-seller in its day in France, not surprising given the amount of salacious material in it, and has retained its popularity since then for that reason (if you remember the Tony Curtis film you'll see how its influence regarding portraying how "Vikings" behaved can still be detected).
Then there is the question of who exactly he was writing about - those who Lewicki's 19th century translation identify as "Russiyah" don't correspond in dress or custom to other accounts of Scandinavian peoples of the 10th century, though there is a fair if incomplete overlap with Germanic and Slavic tribes contained within the description. Thirdly there is the problem of Fadlan's reporting, even given the problem of the poor translation. The entire Risala is a critique, and a very strong critique, of culture outside of islam that the author was reporting back to his peers.
The bottom line is that the funeral as described above does not correspond with any custom verified through archaeological investigation of Scandinavian society's graves of this or any earlier period, either in Scandinavia or along the Russian trade routes. Using it as a point of comparison with other societies' practises is therefore fraught with difficulty bordering on pointlessness. It could be possible that a hybrid culture which comprised elements of Bulgar, Slavic and Viking had asserted itself in the location (modern day Ukraine) which contained such uncharacteristically cruel and salacious elements in its funeral rites, but if it is then it was a culture that has defied archaeological confirmation. It is most definitely not a culture which anyway can be used to generalise about "Vikings" (another term which is something of a bug-bear in Scandinavian historical circles), the burial rites of whom are indeed well researched and show a general consistency over several centuries.
Finally - it is worth noting that if any society was inclined to have had "thrall girls" as depicted above at the time it would have been more likely Ibn Fadlan's, not the Russian societies. The concept of slavery understood by each was very different indeed. Systematic maltreatment of this lowest caste is notable by its absence from the written and archaeological record of Scandinavian societies. Men and women in this caste retained a "man worth" and appeared to lack only the right to voluntarily subscribe to a new fealty. In every other sense they were practically indistuingishable from the bulk of the population who did the basic work. In Arab society a slave was much more completely owned and therefore much more liable to be abused.
Both Fadlan's and Lewicki's readership appears to be the crucial element in assessing any value or point to the Risala. Like a lot of philological evidences it must be understood in the context of its purpose before the extent to which it can be evaluated as a factual record becomes apparent.