In the trademark world you are arguing that "npm" has become "genericized" [1]. That certainly can happen, but that would be a very hard argument to make given npm's relative youth and the lack of true use as a generic. The people you link are either forking the actual npm client (in which case they are referring to it as a proper noun), or are building their own repo architecture, in which case they refer to it as an "npm registry" or "npm repository", not just "an npm".

[1] http://en.wikipedia.org/wiki/Generic_trademark