I think your assumption that the typical demographic for the Mozilla community has a liberal, left wing tendency is probably correct. Therefore it is not surprising that many folks at Mozilla want to see their community engaging in political topics that are unrelated to open source or technology topics - e.g. to support the attempts to redefine the meaning of "marriage" or to serve the feminist agenda by setting up "outreach programs" that create privileged job opportunities for women only.
Of course people at Mozilla are free to do what they want. However they shouldn't label themselves as a "diverse" community then. I am a software developer and actually interested in the technologies Mozilla develops. On the other hand I am also member of a (german) anti-euro party that opposes same-sex marriages or any "gender mainstreaming" measures that the European Union tries to enforce. So as long as Mozilla sees themselves as a lobby group not only for a free web but also for a left-wing social agenda I will not participate and stop further donations.