They weren't deleted, the account was brand new when they were posted so they were probably killed by the spam detector. Questions about stuff like that should just be sent to hn@ycombinator.com, that's in all the site docs.
Nothing like your inference was in my comment, beside the seemingly obvious fact nobody would use such a 'spam detector'. But either way, you can trivially verify this yourself just by looking at /newest.
They are speculating, but there is no telling if it ever even happened. I tend to believe the site's news was just more interesting than what OOP posted.
That's Paul Graham's account, so maybe not just speculation. I didn't realize he still read this site. Not to jump on to OPs paranoia but I kind of thought he was frequenting some secret meta-HN site that still talks about entrepreneurship. Paul, if you see this, let me in! I swear I won't complain about capitalism!
Who knows - maybe different mods have different criteria/bias? Maybe today is a slow day?
I mean, this post isn't really big news, it feels like it's just barely scraping by the notability/interest level required to make it on HN. Mostly, I just think the presence of some kind of cabal or conspiracy is a lot less likely than "mods are human and thus subjective and inconsistent".