My reasoning is that these things are intertwined. Equal rights (race/class/gender/sexuality) is without a doubt the exact same struggle (principally/philosophically) as libre software, knowledge, culture in general. I don't think there's any doubt about that.

Vegetarianism is a bit more far-fetched. But if someone's avoiding the meat industry for ecology/sustainability reasons then I believe they should be just as equally involved with blobfree technology as in animalfree foods. (or - which I'd totally accept - simply avoiding the encumbered technologies)

General leftists etc. should already be both equal rights proponents and vegetarian (with possible exception of meat in a very low-grade sustainable self-reliance manner). So no more arguments are needed there..