Earlier quoted context omitted.
You beat me to it, because I was going to say the same thing; wouldn't it only be carbon neutral if you had some means of guaranteeing that there's no leaks? It seems like converting CO2 to methane could actually make things worse...
If we're converting CO₂ that already exists in the atmosphere, how could it make things worse? Isn't problem making new CO₂ from burning fossil fuels, not converting existing Co2 into other things?
https://www.frontiersin.org/journals/plant-science/articles/...