It's people in agriculture getting worried about "fake" products being sold as equivalent to the real thing. It really got started with the lab cultured "meat" that they're working on. Farmers and ranchers don't want that stuff being sold as "meat". Given their choice they would probably name it "test tube goo" or something like that. Almond milk is considered a cautionary tale. There's really no reason to call it "milk". It's not milk in any way. That's not to say that it's not a viable product, but it is definitely not milk.
I have no idea why the ACLU is getting involved though, that's weird.
It looks like milk is the obvious one here...