To coin a phrase, "it's the song, stupid". No doubt this is a wonderful interpretation, but the song is such a great song that it leaves itself open for many different and valid interpretations. As someone said earlier, it's hard to call one interpretation definitive.
When I saw Bernadette Peters sing "Send in the Clowns" in the ALNM revival, I thought it was the best version I had ever heard, and I had made a point of trying to listen to as many as I could, starting of course with Glynis Johns. But that was a matter of my own taste, I could never call it definitive (though if I recall correctly, some critics may have done just that.)
Great songs allow themselves to be sung in many wonderful ways by great singers.
CZJ at opening night party for A Little Night Music, Dec 13, 2009.