There's no conspiracy, 42Floors just shares the HN blog post links internally and gets people to upvote them. You only need a few quick upvotes to hit the front page, and having a few 42Floors employees vote up 42Floors content is more than enough.

The 42Floors blogposts are generally good quality too, so nobody has any reason to flag them, and they're generally on topic and somewhat interesting, like this one.