There is an enormous difference in scale and efficiency between a lab scale process and an industrial one. Researchers (myself included) do what gets the job done quickly, not necessarily balancing the budget at the same time.
Can we use that pasture-land (and the rain that falls onto it) to grow more useful crops? If so: I don't understand why that wouldn't count.
Given that this is all happening in a lab, is collecting and filtering for reuse an option?
The feed for the cells still has to come from somewhere too, and the growth of the cells is aerobic and generates CO2. That said, artificial meat is supposed to hit market parity price by 2026 and probably below parity after. [1] We will probably see a rapid transition to cultured meat within a decade. There are a very large number of these companies competing right now. [2]
[1] https://www.mitsui.com/mgssi/en/report/detail/__icsFiles/afi... [2] https://cellbasedtech.com/lab-grown-meat-companies
Ah, but are most cows in the world actually grazing on pasture unsuitable for arable farming? I wasn't able to find an estimate of that number, but am willing to bet good money it's pretty low, considering that the number one driver of tropical deforestation is converting land to raise cattle, and the number two driver is soybean production mostly to feed said cattle: https://www.worldwildlife.org/magazine/issues/summer-2018/ar...
If the water savings is mostly nonsense, well then I also question the savings in GHG emissions. Land savings? Sure, fine, that makes sense... but farm land is orders of magnitude cheaper than land that has a fully functioning cell culture factory on it.
In the end, we will know if this works by what price it can sell at and make a marginal return. The jury is out on that one.