It doesn’t read as sarcasm to me. The bulk of the ideas seem “in the right direction”, just with a bunch of gaps and uncertainty. The gaps and uncertainty are where research and conversation live. I read the comment in that spirit.

It's carbon capture isn't it? Use fast growing wood, make furniture by gluing flakes together. If it gets tossed, it just sits underground.

Need to make sure it does not rot (releases methane), or get burned. And that the environmental cost of transportation does not outweigh the benefit. But otherwise it is a potential mechanism, I guess.

Assuming it does stay underground, instead of rotting away in a landfill. GGP said "non-compostable", but I presume they meant "not suitable for composting", and not "physically unable to decay".