That's nice, but they know that idea is not commonly held. The only reason to make a logo for it is to intentionally scare off/irritate people who disagree, further contributing to reddit's homogeneity.
Only amongst those opposed to gay marriage. It is very much a human-rights issue for everyone I know, particularly those who are gay. As for the decisions reddit takes as a site (not the community), they are generally both popular with the community and the admins. Take, for example, the stance they took on running pro-prop 19 ads, or their decision not to run anti-gay marriage ads. The first was genuinely political, but it was also popular. The second was a matter of principle.