The claim here is that almonds are bad for the environment
Veganism isn't carte blanche to do literally anything that doesn't hurt animals directly. If you have a problem with a specific product, even if it contains no animal products, then don't use it. To say there's an issue with product X isn't an attack on veganism just because they typically consume product X.
A cup of dairy milk requires over 10 times the amount of water to produce as almond milk. So, even though water-starved California is using 8% of its water supply in growing the entire US almond supply, it's still three times less water than is used for growing cows in that same state.
"Sustainability tho" is not an acceptable defense to slaughtering calves for veal to harvest the mother's milk, and for starving humans to feed the livestock. There is an inordinate amount of suffering associated with dairy milk even if it were more sustainable.