A little late in the game with this observation and a little OT, but in all fairness to the Manchester Museum, the quote from some journalist's online article appears as just that - a quote from a
journalist.
In the absence of a direct attribution to an official representative of the museum, i.e., the absence of quotations to denote this was told to a journalist verbatim as it appears in the article, I would suggest all they are guilty of is allowing the inaccuracy to go unaddressed, as in turn they are receiving some additional publicitiy - a welcomed gift in this day and age of tightened purse strings.
And of course, curators do get things wrong from time to time, though as a general rule and in the absence of verifiable error* I tend to defer to their knowledge base and depth of archival references, often incorporating their attributions into my own reference library.
As a final note, I personally am thankful for the fallibility of 'experts,' as on more than one occasion, their error has been to my benefit!
*That mirror-finished chrome kukri is obviously one such exception...