I don't really agree with that? People can put aside politics enough to have friends who are quite strongly ideologically different from them; it usually means they agree to not talk politics with each other, unless they're both the type of people who can have heated political discussions and hold no grudges over it. I could bring up personal examples but really you've seen them in the DL! I imagine you've seen them in San Francisco too, because if you're a conservative there you have little choice, just like if you're a liberal in Oklahoma (ask Ciato). And rather famously they do exist in politics too (I remember reading how Obama was good friends with a super-conservative senator from Oklahoma who joined the senate at the same time), even without the obvious excuse of "this person is one of about five people in the world who truly understands the shit that the president of the US goes through" which I think would make one willing to look past rather a lot ideologically.
The "I hate gays" example I understand and I totally see where you're coming from on that, but homophobia and racism are, in their ugliest forms, directed towards specific people and thus very hard to forgive (and even then, they might enter "agree to disagree" territory if the other person isn't gay, black, etc., and they agree to never talk about it... depends on the person). Most other ideological views, even rather extreme ones (e.g. "everyone should pay a flat tax" or "minimum wage should be $20 nationally") are things that most people can forgive in others, even if they strongly disagree.
For the record: I'm not arguing about how close or far apart that the Bush and Clinton families are ideologically, more that you can't really use "but they're friends" to prove how close they are, since there are plenty of examples of people further apart than them who are friends.