The point is that this land was not immutably grassland historically, and so the prior point re: its prior state is not inherently valid. The only question is how long it was the case, if that's what we are meant to care about.
I haven't said anything about whether it's strategically better in this case, that's just a category error re: your reply. I am highlighting that one should avoid the (often settler naturalistic fallacy mindset) that the right thing is what it "used to be", where "used to be" tends to be a somewhat mythological description of the place 50 years ago.