seems to suggest that it is not allowed to obtain KYCed accounts, which to me seems like almost the same thing as what you're describing, but there is no actual hacking involved so I don't know.
The other thing is that some exchanges engage in frivolous KYC demands that are essentiall confiscating customer's funds. While I wouldn't suggest to use fake documents to bypass that, I can imagine why some users with substantial amounts at stake might consider it.
The problem with this service is even though it has good intentions of unlocking your account the way it provides isn't a legal way and it can backfire to the user if the KYC submitted was proven falsified on his end and the exchange might use it against them, permanently locking your funds isn't the worst thing they can do to you. Another point is if this service is really getting this personal information legally from their original owners because I can't really imagine someone will be careless enough to become an "information donor" even if it involves cash in exchange for their private information.
You are only allowed to sell accounts/invites that you legally obtained yourself or through legitimate trades. If you did anything illegal in order to obtain an item, then you can't trade it on bitcointalk.org. Anyone found breaking this rule will be banned.
Also with what theymos said on the thread you provided I think the key word here is "legally" and I don't think their is anything legal about an account being verified with the use of someone else's information.