It's a shame that Dropbox has resorted to attacking its users and threatening them with loss of data. Looks like it's time to clone Dropbox and offer some respectable service to users.
They're said the DMCA was a mistake and they hold their hands up to that. Aside from that, I can't see how they've done anything wrong. OK so asking the author to remove it from 3rd party sites is a bit cheeky, but that's all they did.. ask. I would have asked too, the author didn't have to. He clearly didn't want any trouble.
Imo Dropbox should have just fixed then, and sat there and laughed when people tried to use Dropship and it not work. It would have saved 'Dropbox attempts to kill open source project' and may have even caused for 'Dropbox fixes file hashing issue x days after open source project built to exploit it'. That way, both win. But that's just my 2 cents