option to set minimal privacy level

On the current blogging software that I use, people can set their blogs

private (only they can view it)
followed members only (only people they follow can view it)
members online (only members can view it)
public (even sees it)

This is fine until someone who has 1,000 blog entries decides to make all their entries private or followed members only. I respect that on some sites this is the norm. But I would like an option that would limit which privacy setting were available to my members.

Having a 1,000 blog entries (and all the comments with it) suddenly go 'poof' can dramatically hurt your SEO rating, plus given the false illusion that nothing is going on (falsely appear less active)

^ To clarify, while these options maybe available; I would like the admin option to limit which ones are available.