Before we get any more bent out of shape here…

Twitter Transparency Report Shows U.S. Gov. Makes Most Data Requests | TPM LiveWire

From January to June, U.S. authorities made 902 requests for user information on 1,319 separate Twitter accounts, according to the report.

…and just to put this whole thing in a little bit of perspective, the total number of Twitter users is reported here as 554,750,000, of which 1,319 is 0.00024%. Of course, not all Twitter users are U.S. citizens, but nothing in the Twitter report claims all the subjects of government data requests were U.S. citizens either. Or any of them, for that matter. 

So while your anonymity on Twitter may be of serious—and legitimate—concern, the odds are pretty clearly on your side.