And I am wondering if that is what is behind this, rather than just asking the "non conventionals" to have to point this out to everyone?
But where do you end? There was a man in the USA who 'married' his horse. There was a woman in Germany who 'married' the Berlin Wall. Should we make sure that we consider the feelings of very unconventional people like that and not just make the cavalier assumption, when we need to ask people about spouses, that they will be married to a human? This could be very upsetting to somebody whose spouse is equine or stone rather than human. Before anybody suggests, I'm not being flippant: these people genuinely believe what they affirm.
Incidentally, a great many people - especially older folk - find it deeply upsetting when official forms force them to state 'partner' with no separate option for 'husband/wife/spouse', but nobody cares about them, it would seem. Same with forms that put widowed/divorced as the same category, but again, people for whom this is important can just get stuffed, apparently.
Life is full of assumptions and, as long as there is respect all around, you can't expect never to be in a position to simply state your circumstances without a fuss if they're very unusual.
If somebody started a thread on MN asking for ideas for a simple, free pastime based on what other people enjoyed, and people suggested borrowing books from the library or going for a walk in the park - and then it turned out that the OP was completely blind and had had both legs amputated, would you consider the respondents unreasonable for assuming otherwise, in the absence of any info to the contrary? "Why didn't you ask if I had any legs, rather than just arrogantly assuming, before suggesting walking?"
Even something like veganism is very common nowadays, but you still wouldn't get most people (except for the crazy performance-playdate mum from the other thread) neglecting to mention that fact if they were after for easy meal suggestions. They'd simply state 'looking for quick vegan meal ideas for evenings when I'm late in from work." Only an attention seeker wouldn't mention their plain dietary requirement and wait to hurl abuse at 'omnivonormative' suggestions including meat.
If Warwick Davies weren't well-known and he called a tradesman in to fit a kitchen for him in his absence, would you expect him to mention the fact that he and his wife would want the work surfaces much lower down than standard - or would the tradesman be an assumptive bigot for putting them within the standard height range, without having been given any info to the contrary?
It's very simple and it's all about respect. You can't expect people to magically know, but once you tell them, they should graciously accept that and use that knowledge from then on.