Re: A Zazen question and some worries
I can imagine that it sucks to have been dealing with Tourette's over the years. Mys sensei has an appropriate mantra: "Remember, it's nothing personal." There's a lot in that.
It may not be much of a problem if you are able to manage the auditory tics for longer sits during meditation. Any type of physical tics will likely not be noticed, especially if you are sitting on the periphery of the group. On a deeper level, not being affected by such things is sincerely good practice for others who sit; they get opportunities to let go of each new sound.
As for doing aikido, I can say this: There have been a few people in dojos where I've trained over the years who have had Tourette's-like behaviors (twitching, vocalizations or coughing). Nothing extreme - nothing like the Tourette's of Hollywood.
With all three people, it hasn't been considered a problem by class members or instructors. Literally, not once. If there were, I'm sure it would be dealt with directly and respectfully. I've noticed these peoples' behaviors because I worked with someone who had Tourette's - so to me, it isn't a big mystery. Other people may not notice or care much.
Since you mentioned that you still have some feelings about this, I really commend you for 1) bringing this topic to this board, and 2) for directly confronting this in your own life by doing aikido and meditation.
Aikido pushes all sorts of buttons and people inevitably see all of you, in every form. Maybe what you think is terrible/horrible is not all that to someone else. There are a heck of a LOT worse involuntary behaviors coming out of people on the mat. Everyones' behaviors come out.
Keep training - don't deprive yourself and others.