Confluence should support the ability to set an expiration date on blog posts, at which point it would not show up on any lists using the Blog Post macro (unless perhaps an option is selected to ignore the end date field in the edit macro area).

SharePoint has supported this feature for many years; it's heavily used in our organization (and I'm sure many others), and is preventing us from migrating to Confluence.

Here is how the feature looks in SharePoint:

You should also be able to edit the expiration date when you edit the blog post.