Government is sustained (or abolished) by the people who employ it. Government that can self-sustain seems dangerously close to a government that doesn't need the people it serves.

A government, if it is to serve the people, should only exist as long as the people will it.

If the people present a democratic threat to the government, the government should fade from existence peacefully. If people present a non-democratic threat to the government, then the government should act to protect itself.

Anarchists do not, categorically, present (or seek to present) a non-democratic threat to the democracy.

Do you want to keep tabs on violent* anarchists? Knock yourself out. I have no particular issue with that.

The issue is not that of government is trying to preserve itself. This is a desirable outcome, if all else were equal. The issue is that, in this case preservation was given priority above other goals, among them preserving the right of people to freely associate.