You despise RT. But a lot of others don't. This tool is for them. Of course - you can't make a tool that makes everyone happy. And people who despise RT-ing is not the target audience.
But how is the tool spamming? People who like RT-ing can login. They can select exactly which messages they think are a good fit for their followers. And RT it. The messages they don't like, they don't RT.
Its a reciprocation tool - yes. But why would reciprocation = to spam if its not forced reciprocation?
Ulterior motive: And I am spending time building more apps that are useful, delightful, helpful. If this app succeeds, it will help me promote all those other apps too.