An alternative solution would be to install Stylus or a similar user CSS manager, and add the following user style for stackexchange.com:
.question-container[data-sid="codegolf.stackexchange.com"] { display: none }
This will hide any questions from codegolf.SE from the Filtered Questions list, as well as from the SE.com front page and other similar lists.
Bonus: The following user CSS, applied to any SE sites you visit, will also hide codegolf.SE from the Hot Network Questions sidebar:
#hot-network-questions a[href*="//codegolf.stackexchange.com/"],
#hot-network-questions .favicon.favicon-codegolf { display: none }
(I'm kind of tempted to apply this to puzzling.SE myself.)