I can believe Leno said that, but I am also quite aware that it was a very small minority opinion even among supporters of the legislation.
I'll also note that Leno isn't quoted as saying anything like that in the article you cite to support that Leno said it, though.
> You may not be familiar, but in previous decades, Mark Simpson, Michel Foucault, and many other gay writers were against "gay marriage", often expliciltly arguing it was an embourgeoisement to be rejected.
You are misrepresenting Foucault, who did not argue against (or for, it just simply wasn't a controversy he addressed) equality in marriage but that the limitations (irrespective of sexual preference of the partners) of socially acceptable and institutionalized relationships to only marriage and family-by-descent ought to be lifted and additional forms of relationship recognized and valorized.
Neither did Simpson come from the radical, anti-embourgeoisement, angle you suggest, instead simply buying into the (historically inaccurate) religious right story about the origin of civil marriage and the pro-state-establishment-of-religion argument of the religious right that would give the religious right veto power over the civil definition of religion. That's certainly a viewpoint that exists—and which AFAICT Simpson still holds—but it wasn't a dominant one among LGBTQ activists and allies anytime in the 1999-2011 history of the establishment and expansion of California's Domestic Partnership system. Not even when aggregated with people who did take the radical position you identify, even though neither Simpson nor Foucault are among them.
> Andrew Sullivan and others (with lots of documentary and eyewitness evidence) have written about how they had to move the consensus even among gay people toward marriage equality when it was far away.
I'm not sure why you are pointing to an Slate article that is simply a reprint of one of Sullivan's 1989 articles laying out a conservative case for gay marriage to support your contention that Sullivan and others still had to move the consensus of LGBTQ advocates and allies to support marriage sometime after the time in 2011 when California harmonized domestic partnership with marriage so that the two arguably differed in name only.
Sullivan was certainly important in moving the needle in terms of what people thought was reasonable to set as a near term goal and how they sought to sell it (whether he really shifted the ground on the long-term goal, or just made it seem less quixotic and pie-in-the-sky might be a debate), but he did that well before the time you are referencing.
You spin a fine tale, but it seems to be entirely historical revisionism backed with red herring links and name dropping.