It isn't surprising to me, as I have heard from reliable sources that Bea Arthur could be a royal pain in the you-know-what. She was very abrasive and direct. One story I heard was that early on, Bea was less than kind to Estelle Getty. Bea felt that she was a "novice" when it came to acting, and she sort of made Getty feel she was less than important than she, Betty and Rue. Eventually, she came to be very fond of Estelle, and Estelle of her, but at first, she scared the hell out of Estelle Getty. There are also stories that Bea could be almost nasty to special guest stars as well. She went off on one actor during rehearsals because she saw him chewing gum.
But on the other hand, Bea could be very kind. She just had a few aspects of her personality that didn't necessarily make her "warm" and "friendly", but underneath it all, she could be very sweet, charming and her work for animal rights makes her an "A-OK" human being in my book.
Besides, don't we ALL have our bad days????