I wonder if Loudon Wainwright III rues the day he wrote “Rufus Is a Tit Man,” his jokey, folksy 1975 ode to his infant son’s zeal for breastfeeding. Ever since, Rufus has been proving to Daddy that he is anything but, appearing on the cover of The Advocate, writing songs like “Gay Messiah,” wearing snug-fitting lederhosen (and actually pulling off the look), and releasing a song-by-song tribute to Judy Garland’s famous 1961 concert at Carnegie Hall. (The performance was also filmed for a DVD.) Wainwright père pops up briefly in one of Rufus’ anecdotes during the show, recorded in the summer of 2006, when Rufus tells of his youthful desire to be Dorothy in The Wizard of Oz and how he’d prance around the house wearing an apron: “There are many videos of me with my dad in the background with his Scotch going, ‘Oh my God,’” he quips. Otherwise, Dad doesn’t appear in the performance, but Rufus brings along other family members. Kate McGarrigle, whom Rufus described in a recent interview as his “plain but fabulous Canadian mother,” joins him for a graceful performance of “Over the Rainbow,” while his sister Martha knocks “Stormy Weather” out of the hall. Those appearances help ground the performance, which otherwise could easily have become a feat of ostentatious mimickry. There is a palpable element of camp here, but Rufus’ sincere love for Garland keeps him from slipping into parody; on his fantastic version of “Come Rain or Come Shine,” his jaded-sounding midrange delivery is perfectly suited to sing “Happy together/Unhappy together/Won’t that be fine?” But comparing Rufus’ delivery to Garland’s misses the point; saying that Rufus’ singing lacks the range and punch of Garland’s on “Zing! Went the Strings of My Heart” would be as misguided as saying that Garland’s rendition of “The Man That Got Away” is coldly mechanical compared to Rufus’ sensuous, breathy version. Garland’s 1961 concert is a classic, and Rufus’ performance is a fun, endearing homage. It’s sometimes difficult to remember that Garland was one of the finest performers of her generation, not just a crazy, pinch-faced, barbiturate-popping shrew, and here Rufus, whose own history of addiction and rehab has been well-documented, helps rescue Garland from obscurity and derision for this generation. In so doing, to use dramatic parlance that both Rufus and Judy would appreciate, he has rescued himself.