I am confused, you stated the was up to that point very little risk for regular users at the same time as you said there were protective measures for theymos and staff (and the forum by default). Can you elaborate on the differentiation you stated between them?
Let's make a comparison with drug traffic.
There is a whole network with many people involved at different levels.
At the top, there is the big boss.
There are those who make the drugs.
There are those who handle the logistic.
There are those who sell the drugs.
There are those who watch to warn drug dealers when the cops are coming.
There are also the nannies (sorry I don't know the english word for people who stash drugs at home to make little money).
And there are those who buy drugs (whether they are heavy drug addicts or occasional users).
When the justice wants to dismantle a drug business, they go after the head, the important people and the important elements of the network. They will not arrest all the consumers. But if the justice wants to be zealous, the nannies or the watchers can be sentenced (to minor sanctions).
There with mixers, we don't know with which violence the arm of the justice will strike. Because it will strike one day.
As with drugs, those who have used a mixer for a small amount of money or who have displayed a signature here should not be worried (*). But, again, if the justice wants to be zealous, Bitcointalk as an entity can be considered as part of the network and the forum can be closed. This is the kind of thing, I think, Theymos wants to protect against.
(*) Not a legal advice