[leni536]

Handling and archiving supplementary materials should be the responsibility of the journal (like distributing and archiving the article itself). They should discourage linking to 3rd party websites where the author published his/her work.

I'm pretty sure that Google Code had a TOS where they stated that they don't guarantee that your repository is safe there forever.

There could be several reasons for closing a repository including Google going bankrupt. The availability of a scientific article should be much longer (ideally infinity) than the lifetime of any company.