How do I hide a site from the blog list in BuddyPress

HI! I'd like to hide some sites/blogs from the listing in my Multisite/BuddyPress site.

New members of my network may take some time to completely set up their sites. I don't want empty or messy subsites showing up in my listings at http://www.example.com/sites/.

Ideally I'd like the subsite owner to be able to control this setting, but if I have to do it manually as Super Admin that would be ok.

I know I can use the attributes option and set it to mature, but the site isn't actually "mature" it's just not ready yet! If I use the archived option that hides it from the list but the subsite owner can't log in to keep working on it.

Any ideas please? Thanks!