this needs to be publicly inaccessible, user/member only forum with strict referral membership.
Sorry, even if NES would consider that approach, it simply does not work.
First, the referral suggestion can and has been broken in many ways (member compromised after joining, their account can be broken into and used without their permission or consent, etc.).
Second, this is an internet forum. Using a PM instead of a public posting only gives you a moderate level of security as the PM's are stored on the server and that data could be sub-poenaed (with the proper warrants or with ones based on "national security needs").
Third, your connection to this forum goes over the public internet. Even what you consider a secure connection can be intercepted if somebody decides it's worth breaking into.
Fourth, our government has already shown the capability and willingness to hack into personal systems just because...
And lastly... there in nothing that I've posted on this forum that I would not say directly to any of the people I talked about. Assuming privacy from the government on NES exists is lazy and can only hurt you.
Also, don't assume that our NES fellow got in trouble through this forum (even though it's possible). He could have been flagged in many other ways that have nothing to do with this board (large number of items purchased from multiple dealers reported to gov't, etc.).
Based on the few known facts, this looks like a witch hunt / fishing expedition from the ATF designed to intimidate our entire community, and it should be handled accordingly. I have never been in any of his group buys, but I am sending my contribution to the defense fund today, because he did nothing wrong and deserves our support. You should too...
And I will continue participating in (and even figuring out how to run my own) group buys - we are doing nothing wrong there.