...if their webapp decides to hide a post when the blockchain clearly displays it, then that's as good as saying that it is the app developer's (steemit.com's) intention. It's safe to say that when their "unspoken policy" changes on this subject, they will not hide the posts just because a whale downvoted it--they have the freedom to show it, and it takes more effort from the web development team to hide the post. Once you realize this, you'll see that it is steemit.com's doing. Websites do not have to make their code hide blockchain items...

make sense?

other than that, there are no rules about hiding. I get that. The rules about "hiding" are in steemit.com's web code.