Comment 4 for bug 163116

Disabling the files by removing permissions is causing all apt-get operations involving these files (e.g. an attempt to upgrade to unrelated other security updates) to fail.

Wouldn't it be better to disable the update by removing it from the Packages (and Sources) files (and regenerating the Release and GPG sigs), thereby allowing normal use of the *rest* of the security.ubuntu.com repository?

The rate of related questions in freenode #ubuntu is extreme, even with an appropriate note in the channel topic.