Elton John is a talented musician, but on a different planet from Keith Richards, who is also a talented musician. They’ve both got their personal problems and deficiencies. I fear for Elton John’s “son,” being raised by such a militant unrepentant homosexual. They’re both a little too old for rock & roll now, but there’s no fool like an old fool. I’d expect a catty spat out of Elton John. It’s surprising from Keith Richards.
I would call Keith Richards' response petty. He's had a long history of petty spats going back to his battles with the Beatles. I'm not sure that in this case there is a lot of difference between catty and petty.