Just here to support: English is a constantly evolving language. By way of example, historically, the word jealous has been that you’re afraid of someone taking something from you, like a relationship, it’s something you have, that you may lose due to someone’s influence. The term for wanting what someone else has, is envy. If someone has something you want, you are envious of them. But if you go find the definition for jealousy, it now includes that you want something someone else has, because people have conflated the word jealous with the definition of envy. What happened is that the definition of jealous changed. IMO, I’m not a fan of that one specifically, since we already have a word for envy, but it speaks to my point.
The language adapts to the common usage. Historically, they/them has been used as indirect singular/plural. The change that’s happening now, is that they/them is being used as direct and indirect singular/plural. In the past, the only direct singular for an individual has been he/she/you. There was no direct singular ungendered term, besides “you”, which is only applicable when the subject is the listener. Adding they/them to that is logical, the only alternative I see is to use a brand new word, one likely adapted from another language that already carries that singular and direct meaning. Authoring a new word for something like this isn’t new to English either, since many English words have roots in other languages, which is why grammar rules seem to have (and often do have) more exceptions than anything (like i before e, except after c, or congugating a word with “er” or something similar).
I’m personally a fan of adapting they/them to be direct singular, on top of it’s current use. While it’s uncomfortable for some to use they/them in this manner, myself included, is rather make myself uncomfortable by using that, then make non-binary persons uncomfortable by using pronouns that make them uncomfortable. Besides, the definition of they/them is so close already, that this is a minor adjustment at most. It’s barely an inconvenience.