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Our current scientific understanding in no way leads to such a conclusion.
However, even considering the hypothetical that plants are sentient, eating plants actually causes the least harm seeing as livestock are not very efficient converters of plants to meat.
Currently the number one cause of Amazon rainforest loss is cattle ranching.
Animal agriculture is worse for the environment than plant agriculture. There are numerous studies to support this, here's one, [1].
It is true that animal products at times use land that cannot be well utilized for most plants. But many studies, such as [2], show that this land is unnecessary to feed the world. A vegan diet uses the least amount of land, and excess land can either be utilized for other purposes or returned to nature. Of course there are certain parts of the world which have different capacities to grow different foods, so what I have written is true as a general rule it is not true of literally every location.
It is also true that a vegan diet does kill animals. Though, it kills the fewest animals, even considering field mice and insects killed in the farming process. See [3].
[1] Livestock's Long Shadow - http://www.fao.org/docrep/010/a0701e/a0701e00.HTM
[2] Carrying capacity of U.S. agricultural land: Ten diet scenarios - https://www.elementascience.org/articles/10.12952/journal.el...
[3] Number of Animals Killed to Produce One Million Calories in Eight Food Categories - http://www.animalvisuals.org/projects/data/1mc/
Considering the magnitude of PR this has and will generate, any PR affects, whether positive or negative, will drastically dwarf any cost savings. If they are doing this out of purely self-interest, PR would be the primary concern, not cost.