I purposefully chose an extreme example to put it onto the radar of everyone pushing veganism everywhere. Also if you really study sustainability, you see that reducing meat production doesn't lead to better sustainability anyway.

If you reduce meat production, you'll hike up prices, likely pricing out those with autoimmune diseases that barely survive already. So technically you are true like in "you can still eat meat in theory", but in practice those folks won't be able. Now where is the good faith in that argument?