Great! I love this!
Other than servers obviously set up for bots/spam we aim to not defederate. We will even federate with bot instances if the community wishes. Though I find that incredibly unlikely.
I like the mission, but true "universality" might be too ambitious. In my own instance I implement a very open federation policy, and I've already experienced that some situations can get tricky. At the moment an example of a tricky situation (for me) is federation with threads, which presents a new set of potential problems that are different than the problems that I had originally considered when thinking about open federation.
In a forward-thinking manner, you may want to think about the liabilities that you will be exposed to if you federate with instances in which illegal content is posted, or in which illegal activities take place (drug and weapon trade, doxxing, discussions about how to run scams, fraud, etc). You should also think about the type of content that crosses the line for you (even if not illegal - things like gore and pornographic drawings of child-like cartoons) and reflect about whether you would be comfortable having the thumbnails of images that cross your personal boundaries copied to your server.
I think it would be a good idea to state your intention towards universality, but don't remove your ability of being able to apply common sense. A dogmatic universal promise might back-fire later on when you feel the need to take back your own power. I think that the idea of universal open federation works best when you run your own single-user instance, or share your instance with a few friends, because then you have full control over what you actually fetch.