> So we could agree that the methane is irrelevant because it would be emitted anyway by the rotting grass.
Natural forests and grasslands don't decay in a manner that emit a lot of methane. Cows on the other hand emit a lot of methane, due to how they digest their food.
> And we could also agree that clearing forests is a different thing than farming meat, which we could separately campaign against and prevent.
The data is about where current emissions come from. It is not directly suggesting any policy prescriptions, or directly stating what emissions will be under alternate food choices.
Yes, clearing forests is different from farming meat. But the best place to plant new trees in sustainable manner, in order to capture some of excess CO2 human activity causes, is where forests grew a few decades or centuries ago. Many of these places are currently occupied by cattle ranches or farms that grow food for cattle. One reasonable policy prescription would be to reduce beef demand/supply, and then incentivize tree plantation in those areas.