But did you read the article?
They didn't get permission - DH wouldn't talk to them. And they had previously had a takedown notice with the 'sailing much closer to the wind' NHSbuntu branding.
They also didn't try and pass themselves off as being part of the NHS (unlike so many commercial companies that pretend to be NHS like DHL etc), and they didn't use the NHS logo.
Just reading the DH letter gives a rather one sided story, as you might expect!