No it's not petty at all. While I don't think there's that many people would take up arms to defend their right to buy steak (especially if their lives improve on every other front), it's entirely possible that the struggle for vegan socialism will be a twenty, forty, or even sixty year project on top of getting to the socialist state in the first place and it almost certainly won't be for the animals. Alternatively it could arise out of protracted people's war and the breakdown of supply lines making animal products an unobtainable luxury. Surely there are other ways, but I don't know what conditions will produce this change. Like so many features of higher stage communism though, we need socialism before we could even hope to end animal agriculture so that people become educated and conditioned to it just like the withering of the state or the end of the value-form.