I think GP is suggesting that, for a better picture, you also need to include stuff like the CO2 emissions from the vitamins you’ll need to eat to balance the nutritional deficit. Given how bad meat is for the environment, it wouldn’t surprise me that the total balance is still way worse for meat.

Somehow I feel the need to clarify I’m not shilling for beef, but extra vitamins is something that my vegetarian SO constantly has to be keep in mind.