No, I think I was wrong that Tumblr is back on the app store. I obviously didn’t read whatever article properly; Tumblr said Apple pulled the app because they were failing to censor kiddie porn, but they didn’t say when they’d resolve that.
Though, AFAIA there’s still no reason to think that Apple are the cause of this policy. I doubt being in Apple’s app store could possibly help Tumblr’s user retention as much as banning bikini secrets will harm them. (And the iOS app is little different to tumblr’s web UX anyway).
I could be wrong; it’d be good to know. I have seen a sort-of-dating social site crack down on “explicit content” because they were bringing out an iOS app, even though Apple’s published rules didn’t appear to require it. So at the very least Apple do need to be clear what they will and won’t reject (albeit, developers need to consult Apple’s developer portal rather than third-hand rumors on reddit and stackoverflow).
Anyway, the world really doesn’t need input from any giant American businesses regarding sex.