Not having seen it I offer up no opinion on what Richardson did or should have said, and I don't offer this up as any kind of defense.
But in general terms, focusing on the record is something we should do more instead of trying to divine what's in the souls of candidates. There are reasons for doing the latter, as past performance is no guarantee of future returns, but ultimately it doesn't really matter what politicians think about things deep in their hearts. Bill Richardson can think (not saying he does) that homosexuality is an abomination which will be punished by an eternity in hell, as long as he's pushing for policies which provide gays and lesbians with equal rights.