Precisely! Not what OP's political views are but I would guess if he found the Midwest "stifling" and SF "a breath of fresh air", it's because he's aligned with the politics in SF.
Having also lived in the mid-West and SF, I would agree the mid-West leans more conservative, but in any decent sized city you'll find both view points (election resulted confirm it).
I would say SF is just the opposite of a hardcore conservative town. There is almost no consideration for having a different viewpoint. And if you happen to express one, you're certainly made to feel their is something wrong with you.
This is definitely not my experience. Your framing that there are only two significant viewpoints (thus, "both") is exactly part of what I was glad to get away from.
There are many different sets of "social values and political ideologies" in the Bay Area. That was the glory of it for me. I have met all sorts of radicals and artists and weirdos here. And plenty of perfectly normal people, but whose notions of "normal" don't overlap all that much. E.g., the Lebanese-American family that ran a store in my neighborhood. The Latino family in the apartment next door. GLBT families far more into normcore than I'll ever be. Etc, etc.
I think the problem with both the WSJ piece and your approach is that "social values and political ideologies" is some sort of code, an attempt to frame a very particular strain of conservativism as just another kind of viewpoint while carefully not looking at the contents of that strain.
The only viewpoints I've seen people be actively hostile to here are ones that already include active hostility to other people. If you start out with some anti-gay slurs in the Castro, for example, and you will definitely be made to feel that there is something wrong with you. And that's not shocking to me at all; after a lifetime of hostility and abuse from self-proclaimed conservatives, gay people are quite reasonably sensitive.
(Not American and don't live in either place you describe.)
Is that feeling of pushback to an (assumed) different viewpoint just that in the midwest, a conservative is in the majority, and in SF they're not? So, in one place you'd encounter almost no confident opposition, and in the other you would? I assume it might stand out and feel like suppression if you weren't at all used to it.
I suspect that's part of it for sure. A lot of what conservatives have been getting upset about over the last few decades is diffusion of power away from well-off, white, straight men to everybody else. Loss of power still feels like a personal loss, even if systemically it's a move toward a more equal structure.
Having also lived in the mid-West and SF, I would agree the mid-West leans more conservative, but in any decent sized city you'll find both view points (election resulted confirm it).
I would say SF is just the opposite of a hardcore conservative town. There is almost no consideration for having a different viewpoint. And if you happen to express one, you're certainly made to feel their is something wrong with you.