I wrote it and I'll respond - I do like the concept of a Bloom Filter and do think it's a pretty good solution to this problem but I don't really expect anyone to get to that stage on their own - and very few people do. What I use it for is as a destination and when we finally get there we get to talk about it. You can get a sense of how good a developer is based on how quickly they grasp the concept as well as the discussion that ensues.

I view an interview as more of a conversation and love learning about new concepts.

I think any question can be dangerous in the wrong hands and suffer from the "guess the answer I'm looking for" so it's always up to the interviewer to be unbiased.