It seems like its still safe to refer to someone of gender unknown as "they/them".
It actually normalises the use of those pronouns which makes it simpler for people iddntifying as non-binary too.
I don't mean that it's unsafe, just that it's somehow become controversial or at least less usual, people laboriously writing 'he or she' where I'm sure they wouldn't have ten years ago; 'they' isn't a modern invention it was always fine, and I suppose for the modern world is more inclusive than 'he or she' anyway!