I should hope that calling someone a "sexy married woman" would not intend to imply that she's a valid candidate for sex. Not that it's particularly tasteful either.
I take it you're suggesting that his acknowledgment of her marriage implies an obvious understanding that she is not available as a sexual candidate, but his reference to her as sexy still reveals his approval of her appearance with regard to her value as a sexual partner for anyone (in this case, her new husband, who he points out is lucky to have her)
