I suppose I don't disagree, but I don't think realistic vs. unrealistic is the right way to frame this. Questions like "should we eat meat" or "should we promote having kids" are huge, cross-cutting issues which strike to the heart of what we value as a society. The idea that you could analyze them solely in terms of the climate, that climate concerns would compel us to ban meat if it were politically feasible, is already fundamentally confused.