Gatekeeping is part of running a project -- you have the right to refuse the contributions for any reason you'd like. They, likewise, have the right to fork you

Gatekeeping is part of running a project -- you have the right to refuse the contributions for any reason you'd like. They, likewise, have the right to fork your project and run a new one how they see fit. Do it too much though, and you'll drive the popularity of your project way down and nobody will use it. Even with free (in both senses of the word) products, the market will always work itself out.