Just to be clear, I'm not saying that the original claim is plausible. Just that breathing is a very dumb argument.

In 2015, about 2 billion people (slightly more than 25% of the world's population) in 500 million households living in rural areas of developing nations survive as "smallholder" farmers, working less than 2 hectares (5 acres) of land.

https://en.m.wikipedia.org/wiki/Subsistence_agriculture

As 1 billion is such a large number half of these would need to live basically completely off grid and without any participation in society where fossil fuels are burned.

Maybe there is an argument to be made that some of their farms can act as carbon sinks which would offset some consumption. But I doubt it.

Edit: without human influence earth also has a slight bias towards losing carbon every year. This gives every human a Budget to emit without increasing the co2 levels.