I have taught of this seriously and I began to have a biased concern to bitcointalk if any signatures campaigns in bitcointalk can affects the existence of bitcointalk if they commit a crime that leads to government investigations.
I don't think any form of signature campaign can actually affect the forum. This is because the forum is an open area where spam is not moderated. You as an individual have the right to wear whatever you want under your signature space. If by any chance what you advertise under your signature space turns out to be illegal and attracts the government's attention, that's between you and the project. To be on the safe side, all you should do is take off the signature code. Even if an investigation is to be made, it won't come directly to the forum, but it might have an individual attack on you, who was advertising the project in the first place, because those government officials will not agree that you don't know anything about the project. (But I doubt that can even happen.)
I believe one of the reasons why the forum stopped showing off ads is because of this kind of risk and to be on the safer side, not to directly advertise any project that might turn out to give the forum a bad name.
Secondly do we believe that bitcointalk can be obstructed by government if their is a noticeable crime by the management?.
I never believed it before, until the CM issue, when I came across a discussion where one of the respected members made mention of such things as "that we should be prepared and we might actually see a similar welcome news here on the forum one day."
I would say it's possible, but that will only be if the government has enough reason to do that, although I know these days the SEC doesn't actually need reasons to do something; they just create one.
So I believe there are fewer things to worry about; the forum is organic and is not a direct threat to any government.