I would phrase it that open source is just about the license of code, not about anything else, and definitely not about how changes are applied to such code.
Usually, it just practically means that you are allowed to make changes and redistribute them, but without giving any guarantees on how these changes are going to be made available to others.
No, it's about Clojure. It's not in any way about open source. Software can be open source no matter how the person writing it runs their projects.