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".
Even without a trademark, the npm source has been Artistic License v2 for as long as I can remember, so any forks are obligated to change their name to have the right to forking the source code.
And what about alternate npm-compatible registries (https://github.com/mbrevoort/node-reggie, https://github.com/rlidwka/sinopia, https://github.com/cnpm/cnpmjs.org), not based on CouchDB?
"npm" isn't only a product name anymore since it's used extremely widely, so this doesn't seem like a good thing to do.