24 June 1982 Dear Comrade Deng,
Though I can produce no evidence, I feel that the "Yes" as a reply to your "It's not bad" is correct. "Not bad" is almost a fixed phrase = "quite good" or "fairly good" and is different from "not clever", "not happy", "not a boy" etc, all of which are semantically opposed to "clever", "happy", "boy".
"... So what did it matter if she was married or not?" Is now very common, if still condemned by some people. After all, what is condemned actually exists.
Incidentally, "so what did it matter if or not she was married" would sound worse, though it is not impossible in informal style. Certainly it is more condemned than" if ... or not ". You might say I seem to be non-committal. But usage is something that one often has to be non-committal about.
With best wishes, Yours sincerely, Ge Chuangui