Tolerance extends to the understanding of a culture and abstaining from deriding someone based solely on that culture.
The joke, which reveals a deeper personal value judgement on behalf of the person telling it, speaks of a "good gay" as if to stereotype gay men by a particular behavior, denying the possibility that you can be a "good" gay man but have a different cultural outlook. That, to me, is unquestionably a form of intolerance. Making light of someone can be a form of intolerance, depending on what property it is by which you make light of them and whether or not it is based in a harmful generalization. Another way to say it is: you can't claim tolerance if you're happy to propagate harmful stereotypes or generalizations.
Emphatically, it is crucial to dive into the language deeply. The urge to say "it's just a joke" is precisely the kind of let's-sweep-this-frat-house-bigotry-under-the-rug-and-go-back-to-thinking-everything's-nice rationalization that allows such bigotry to perpetuate.
Re: your last line that it's like gossip:
Except that this is our political process. It happens rarely (once per four years) and is a matter of passion, contention, and deep moral conviction. We have every right to expect it to be held to far higher standard than some bullshit gossip.
Let me be clear that I do not believe it's merely gossip and I'm not offering any credibility to that stance. It's not mere gossip. It is harmful, derogatory language about gays, as well as at the very least an amazingly insensitive and offensive simplification of American religious beliefs (e.g., that some particular Christian people will see "a Jew" differently than "an atheist" and that could be worth a few polling points, and that all three belief groups are nothing whatsoever but sources of polling points, to be engineered and manipulated with audience plants, etc.)
But even if it was "mere gossip" [it isn't] it would still be outrageously flagrant that the primary administrators of one half of our most important political process essentially view their jobs as a frat party. That's not some kind of let's-roll-our-eyes-but-boys-will-be-boys-and-move-on kind of thing, as you seem to think it is, but rather it is a let's-eject-everyone-from-this-Neanderthal-administration-and-hire-people-who-actually-give-a-damn issue. It's not boring nightly news to be eye-rolled and skipped for the sports section. It's our goddamn political process. It's frankly shocking to me that someone would suggest it's just boring gossip to be unconcerned with. I cannot reconcile that with any notion of caring about even the tiniest component of civic duty.