Plants are not beings under any standard usage of the word. While plants certainly communicate and show some level of computational processing, there is no evidence they have subjective experiences. There is a very clearly line to be drawn between plants and animals.

And if that's not a compelling enough counterargument, there are two additional issues with trying to conflate plants and animals in this context. First, it takes far more plants to support an omnivorous diet than a plant-based diet. Second, many plant-based products are obtainable without having to harm the plant.