It's part of the NSA's recruiting push. "If you are interested in projects like this ... consider applying" is even mentioned in the README.

There's zero chance there's some secret trojan, because the people who are interested in this type of software are the exact people who would be able to find it.

Fortunately, a lot of people who are very knowledgeable about reverse engineering are downloading & opening it as we speak. They will point out any flaws/viruses found. Seems one has already been found [1]. All you need to do is to wait.

[1]: https://news.ycombinator.com/item?id=19315515