I don't think it's really a big deal. Since the list is signed, an active attacker would only be able to replay an old version of the list... but it's hard to see how that would be worse than just blocking the request entirely.
True, but it might be slightly less visible because you'd get an "update" instead of a failure. Also, I wonder if anyone has actually tested that scenario?
I'd like to believe that's true and that should be true, but I'd also have to actually test it before trusting it to be true.