Here is a problem: It's impossible to catch all sock puppets just by activity or taint analysis. You can't even do taint analysis with Nxt investors as all accounts are connected closely via exchanges such as Bter and Dgex. Plus it's really easy to fool the system by transferring BTC to an exchanges and back.
As for account activity, people can have more than one active account that they use to post.
This. This makes the whole issue irrelevant.
As well there's no conclusive proof that inactive accounts are sockpuppets. There's many people who lurk and read Bitcointalk but simply aren't interested in any discussion on here. The "call for participation" wasn't intended literally, it was legal wording to get out of any financial liability for running a securities. While someone might not be active on Bitcointalk - they may be active on other social media websites or be really effective in viral P2P advertising.
My point is that we have too many "group 3", retroactively taking away their stakes (these people waited half a year) means NEM is going to create a lot of enemies overnight and I think that's more FUD worthy than any sockmaster boogeymen. We know in NODE's case that (we take away the bull$hit intuition examples), they only found an extremely small number (compared to 1000 stakeholders) of sockpuppets. So I stand by my conclusion that taking away stakes in mass is just going to piss off people and they'll be NEMs' worst enemies and they'll talk away any subsequent interested people.
The original issue here was someone scammed Pat of 6 or 8 tokens but that has nothing to do with sockpuppets, that was some guy who was looking up names on the stakeholder list and creating a copy cat name which look the same.
Then the people photoshopping banned photos to get NEMstake.
You know NEM must be really promising if people are resorting to weird ways to get it.
We don't have to take their stakes away, but we should try to at least message them and give them a chance to respond. Like ask them if they are a sock puppet, if so, who's account (up to 2 accounts controlled by 1 person is okay in the rules). If there are no replies, then we can consider taking stakes away, or if we can find proof that a person has more than 2 accounts.