No, the author doesn't try to limit anyone's freedom, he only asks people to understand him and to work against proprietary platforms, not prohibits them to do anything.
He just says that he won't do it and explains why you should not either. That's hardly limiting you from doing anything.
Even though I don't agree with his position (I fit in the "I don't care if it works on Windows or not, if you care pull requests are always welcome" camp), it's a reasonable one to have.
Of course he does. By choosing a GNU license he explicitly limits the choices available to anyone that might make use of his software in their own software projects. That's the whole point of the license to limit the freedoms of developers in favor of users... his favored group. Even then, his plea is for developers to willingly limit user choice in regard to proprietary software. Sure, his license doesn't legally prevent this, but he's asking developers to de facto limit user freedom to choose their operating environment in favor of his approved systems.
If he were merely trying to convince users to move to Libre systems while making no plea to the developers that might otherwise enable users to choose against his wishes, you might have a point: but that's not his goal.
He then goes on to say that he won't permit his software to be compatible with other platforms like Visual Studio, _even at the cost of performance_.
If that's not cutting your nose off to spite your face, it's still definitely a direct attempt to limit your freedom.