What is the use for a 'logo' that can be copy-pasted into text? If you write text you can just use the name - fediverse. Its like they get the worst of both worlds; a bad logo that is not even theirs but is an unicode character. And a shitty way of writing their name that makes it incomprehensible to outsiders.
The rationale for having symbols I feel is so self-evident it shouldn't need any explanation. You know the save icon, you know the power button, you know the Twitter, well, X logo. You probably know the 'share' icon. I don't know if anyone's going to buy that it's bad to have a simple universal icon closely associated with a specific thing that we want widely known. And Unicode has an advantage over images of being, in a sense, more universal and more accessible.