Block? No.

Though crudely you could have the search results only show you questions over a certain score:

> [score:>2 is:q](http://superuser.com/search?tab=newest&q=score%3a%3e2%20is%3aq "eats like a sea urchin")

(make sure "newest" tab is selected) but this will not update in real-time if you're used to that.