The language has evolved. The singular they filled a hole in the language that needed to be filled. I think the only people who are still against using it are likely the ones who don't like it when language evolves. They want it to stay the way their teachers taught them, likely out of a textbook that predated the change. Unfortunately for them, evolution is a constant process. Language is defined by the people who use it, not by the teachers and textbook writers.

I've worked on two films shot there over the past 10 years. It has been sad watching the place fall apart. There are areas where the top floor has fallen down to the bottom floor. I've heard talk of an attempt to save the building, but it will probably cost a few million dollars and it sounds like nobody involved has that kind of money.