Sorry, that sentence was confusing. :/ It wasn't really meant to say anything at all. The "filter" that we're focusing on is a statistical property of planets in general, and it's this property of planets in general that we're trying to evaluate. What happened on Earth has no bearing on that question.

That sentence was also confusing because it made it sound like a filter would happen on Earth, which is not necessarily the case. I edited to say "We know the filter on Earth (if any)", adding the "if any" part.