To directly answer the question in the subject: of course Yaron's extensions should stay in gerrit.wikimedia.org, without the file in question.
We want MediaWiki's main development spaces to be inclusive and able to bring developers together. I think we all agree that it's a loss if more repositories end up being scattered on third party git servers.
Meddling with the content of repositories we host by forcing Wikimedia-specific content is not responsible. For one, it makes it impossible to multi-host a repository if such Wikimedia-specific content is incompatible with the requirements of other hosts.
Federico