I find absurdly picky eaters annoying and exhausting, mainly those that go to places where they should know better (like this Chinese restaurant no doubt). They unfairly give food aversions and picky eating a bad name as a whole.
I too could be described as a “texture-sensitive super-taster”, and I think that most people just don’t realize what it’s like. For a particular person’s worst aversions, attempting to eat them activates the involuntary gag reflex (sometimes just contemplating eating them is enough). What does anyone honestly expect that person to do? If it’s something truly unavoidable (few things fall into that category thankfully), the person can probably train themselves to not gag, but it can take a lot of effort and they’ll probably need to do that at home (you can guess that the chances of it happening are not great) not in a social setting where people are saying “come on, try it” or whatever.
The one non-seafood thing that really does it for me still as an adult (late 20s) is squash, any type. Can’t do it. As others have written about, that does have something to do with a particular childhood experience I still remember vividly, but it’s not just that. From your list I also don’t usually do mayo-based salads (it took me a while to realize what that meant, haha), and I eat eggs occasionally but I too get the very strong sulfur taste. Some bitter green stuff (kale, brussels sprouts) are ok (not when I was a kid, but now) but most salads are right out, for my next reason…
I despise vinegar - it doesn’t make me feel like retching, so it’s different, this is more of a supertaster thing… I’m so sensitive to vinegar even a tiny amount overpowers every other flavor. I can eat it, it’s just rather unpleasant. There are some cases where I can’t taste it very strongly, but I’m not exactly sure why, must react with something to soften it - but, for example, I can taste it when it’s the base of even the hottest of hot sauces. Put sriracha, though, which normally I don’t use because it’s vinegary, into pho and it’s really good - don’t know.
As for texture… that’s the main reason I don’t like most seafood. In the worst cases this still activates a gag reflex for me. I can’t fathom eating a shrimp. Also, I get that fishy taste really, really strongly. I really like some types of sashimi, though, when it’s nice and fresh - you can’t assume anything about picky eaters (no octopus etc. though, thank you).
Like you, I’m now quite an eclectic, adventurous eater, probably far more so than most of the people who have goaded me to eat one thing or another over the years. Like you hint at, part of that is probably due to being excluded from many extremely popular things (like salad) and having to look for alternatives. Not eating most seafood is somewhat limiting, especially in the various Asian cuisines, which I’ve been surrounded with for ten years or so because of my social circle and various places I’ve lived - I’ve tried a lot of weird things. I’m OK with that though - there’s always something different.
I too get migraines, though not chronic. Certain foods can trigger them although for me it has to be something really overwhelming (or caffeine, which I cut out completely a few months ago after not realizing it was my primary migraine trigger my whole life previously because I drank it so much…). If I already have a bad migraine, even foods I normally like can make me nauseous just from looking at them, and things I don’t like would be just awful.
Finally, unless you’re one of those people with the ridiculous substitutions and complicated orders (I assume you’re not self-aware if you’re like that), it’s really rather embarrassing to be a picky eater. When people respond with ridicule or complete lack of understanding, it feels really, really bad. Potential friendships are ruined. I know it’s tough because of the really annoying picky eaters, but just don’t assume anything, don’t be a dick, and if you are annoyed just avoid that person - no harm there.