I would guess that there are many different roles in the military that isn't about shooting enemies in the face with a rifle, like communication, logistics, clearing mines and many more. Ukraine is also conscripting so even if you would rather not be in the military you might not have a choice. Having food that aligns with people's personal beliefs show that they actually respect their citizens beliefs in the ways they can even in the shitty situation that has been forced upon them. Russia would probably not do this.