If they had kids to take care of at the time, I hope they did not spend an entire afternoon working on it without success. And if they took so much time documenting their steps that it made the project take so long they could not complete it, I would say that is a negative indicator.
In the end, IIRC it wasn't that hard a test for the sort of person who would be good at the job, so it seems like a reasonable filter. The only good reasons for not successfully completing it were 1) You didn't have time for it, or 2) You simply aren't ready at this point in your career.
I'd like to note that I have yet to pass the test - my first and only attempt was a curl one-liner that I gave up on when I realized I had work to complete :D.
In the end, IIRC it wasn't that hard a test for the sort of person who would be good at the job, so it seems like a reasonable filter. The only good reasons for not successfully completing it were 1) You didn't have time for it, or 2) You simply aren't ready at this point in your career.