It's not a fuss about nothing, and the hidden disability lanyards are a minefield too.
I'll tell you a tale of when I got on a train, with a lanyard and my ear defenders on.
It was loud, so I put on my ear defenders, I missed over the tannoy that the train would have to divert to a different station and would be terminating there. Everyone got off the train en masse, which confused me and the conductor came up to me, removed my ear defenders and said "maybe if you weren't wearing those stupid things you'd know you need to get off. It's always the same with YOU PEOPLE", so I had to get off the train, in a panic, at a destination I had absolutely no idea of, no phone signal, everyone avoiding me because I had outed myself as disabled. I'll spare the rest of the story because it's quite traumatic, but yes wearing disability lanyards, or anything that can out you as disabled outrightly does get you targeted for discrimination.
I had another incidednt where I wore my lanyard in a shop, and the cashier started speaking to me really slowly and loudly, even though I told her I can hear her just fine, yes I would like it if she could put the things in the bag for me, and she held the queue up, while people just stared at me as though I was the cause of the hold up.
We get enough guff for being disabled and trying to highlight we need accomodations, without our employers adding to this.
Stating your neurodivergence in your email sign offs will absoslutely cause people to misunderstand, misinterpret, intentionally change your words, talk down to you, discriminate against you, avoid you, and even cause tensions if you have reasonable adjustment accomodations that they feel they should also be entitled to. It puts a big fat plumbob on your head as a "special one", so people know who exactly to direct their vitriol towards.
So optional or not, it is the employers responsibility to manage each person on an individual basis without pointing it out to all and sundry. It doesn't matter whether the indication is a physical indication or a digital one. The employer can't expect all it's employees to know or understand the varying needs of neurodivergence.