Re: Is this just an English thing ?
They is commonly used in the singular, e.g. ' I don't t know who left this wallet here but they are going to be unhappy when they find it missing'.
I don't subscribe to other people's codes of conduct, I have my own.
Regardless of gender, self identified or otherwise, or race, religion etc I treat everyone with reasonable respect unless they demonstrate it is undeserved.
I don't care if a 250lb body builder has a huge beard and wears a tutu, I do care if he/she/it is rude to me or sits on my lap.
My wife would be furious.