Yes it is. And so is Twister. But the millions who use Twitter to quietly follow people/things could potentially be profiled [1] and labeled ''terrorist™'' by association.

> Twister is designed to prevent other users from knowing (...) who you follow.

Essentially, Twister prevents the NSA from profiling you as an 'undesirable' based on who you follow.

[1] http://www.cs.umd.edu/~golbeck/pubs/Golbeck%20et%20al.%20-%2...