The aim of developing Rust is to make the world closer to a certain ideal world. This ideal world is an ideology, and some people could find it is not ideal. This ideal world seems to have these properties:
- people do not fear bugs or panics while using a computer;
- computers are more useful because programs are faster and lighter;
- things are interoperable;
- developers can use free software;
- etc.
If you think these properties are intrinsically good (or are consequences of intrinsically good properties), being rational means acting the way which will the most probably make them them real. Rust may be a part of the solution, so it is rational to develop it.
Let's assume a group of people starts a project of which the target is this ideal world. It's absolutely legitimate that they express these political opinions using the project's official label, because these opinions are the core of the project. (e.g. stop a contract with a company because this company is harmful for free software developers) But if they express opinions that are not consequences of the project's ideology (either incompatible or unrelated), this is unfair. (e.g. death penalty for murderers or free license prohibition)