How are they supposed to eat? That is their main job. These people are now trying to starve cows.
Also: I hate that article. Humans have lived with cattle since the dawn of time, be it hunting herds of buffalo, or farming domesticated cattle.
Eating meat helped us survive the last big ice-age, and increased out brain capacity. Also grain and vegetable eaters eat more: They have to, because the food is less nutrient dense and is less absorbable. They also have to spend longer hours preparing food.
The real agenda here is to starve the planet. Replacing cattle with grain is not actually feasible, even if one wanted to (I don't) because cattle and other farm animals graze pastures that are often not viable as agricultural land, e.g. steep pasture. Furthermore, grain and vegetables use more water and fertilizer, not to mention kill thousands of small creatures. The people who bloviate about reducing consumption of meat, fail to see that only starving populations subsist on grain, pulses and vegetables out of necessity.
How are they supposed to eat? That is their main job.