Thank you very much for the answer Jon. That's definitely helpful!
I came to the result that it might be the best to make a global setting where the user can decide if font-awsome should get loaded or not. In my point of view it's currently the only way that isn't described in the stackoverflow post as dirty or bad and prevents the plugin to load the css if not required.
I've now created a post in the general developer forum since I'm looking for a proper automatic solution.