I think one of the issues is the title is too generic. Maybe call out some specific schools on the tour next time?

Is there a requirement that YC announcements perform well? I'm not trying to be negative, but just announce all the tours the same way and let people make of it what they will.

No requirement. But why not try something different if the first version doesn't work well?

If the point is just to announce, then why change what you did before? Announce it through the normal channels and be done with it.

Why can't a 'super user' just pin something at the top?

They could, but I'm glad they don't by policy.

I can't imagine the amount of crying from the community if the hosts of the site would take special privilege to pin their posts at the top. (I'd be fine with it, as it's their house, but I think they actually are better served to only take a small privilege with the jobs and show posts and otherwise leave the site to the users to vote/curate.)