Information obtained after the DMCA takedown request was issued shouldn't affect whether or not the request was made in good faith ex post facto. Currently there are no penalties (specified in the DMCA) for not withdrawing the request once it's become clear that it's bogus. There may be other ways under the law to get punished for a lack of action though. E.g. there may be case-law that states you can be penalized for a good faith action if you don't make motions to correct the mistake once you realize it.
Yeah, I understand how it is currently. I was saying it should (in a perfect world) be a much harder battle to prove you were acting in good faith if you are provided clear evidence that your request is completely wrong and you fail to redress the claim. The time period for a take down can cause a lot of harm to sites in exactly the same way that leaving up infringing stuff can.
