I'm perpetually logged in: whenever I visit hubski, I'm just continuing where I left off without signing out. That said, I may not be comprehending your use of "logged out," nor it's function in the suggested feature. My understanding of your suggestion is users visiting the site without logging in have new user posts not showing up by default? If so, it serves to benefit those logged in with added functionality of toggling, which we have. I think I'm missing something. :o
I'm also perpetually logged in, I just tested the site logged out today to see the difference and it was huge. Maybe it is possible to give that toggle option to logged out users too, save it in their session until they clear the cookies, have it off by default. I am saying this from previous experience as a reddit lurker, as someone who wanted to consume information instead of producing it. Logged out users mostly read what's "hot" or "trending", they rarely go to "new" or "global" so I doubt many of them will be affected by defaulting to have < 2 days old accounts hidden and if it is possible to add an option to toggle it then they won't be affected at all.