You didn’t misunderstand. Here (and check out the two comments before this one):
On this same page this is David’s comment that seems to indicate that this threat potentially can be dealt with (i.e. isn’t dealt with in any way right now, as far as I can tell from the comment).
Reading the later comment (the first URL) I understand that encrypting public file chunks with the last node’s public key isn’t going to be useful when the node before the last knows its content and the last node’s IP address.
Of course they aren’t that stupid. They need to ensure your MaidSafe package contains the “right” keys. While I doubt they’d use that to catch some Piratebay schmucks, more serious users can be targeted this way.
Okay, I look forward to explanations about those public data chunks…