I while ago I rand some relatively unscientific numbers, and learned that even swamps and forests are relatively inefficient users of space as it pertained to carbon capture. For example, a well managed bamboo plantation will yield 25T/hectare/year of bamboo, and this includes quite a bit of labour for the management. Meanwhile, the same area, covered in solar panels, will get you to around 500MWh per year of produced capacity.
The world emissions per capita are presently around 5T per year, per capita. The world has 5 billion hectares (out of 13B total) of agricultural land in general, overall (and generally if land _could_ be used for agriculture it _is_ used for agriculture), so generally, there's not a tonne of space to do lots of carbon sequestering quickly with agriculture, especially as you'd need to move the carbon you've created somewhere else.
The moral is that if you can ever get sequestering carbon down such that you can sequester 1 tonne of carbon for 20MWh power, you're close to a major winner, at least in all the deserts where you clearly can't grow bamboo but can grow solar, because at that point your cost of operations is just cost of infra. That startup thinks it can get down to around 1MWh/tonne, which is comparatively awesome!
My conclusion (before getting to something super scientific) was that if you want to rely on trees and swamps for your carbon capture, you basically end up with massive geopolitical issues because you need to cover most of the world in trees and swamps, but most of the world's land is already used to grow food.
Meanwhile, carbon capture can work in areas where land is not (as) valuable.
If they are able to get to $50/tonne, that implies 1MWh/tonne, so that's about 500 tonnes/year per hectare. That'd mean that if you covered arizona in solar panels, you'd be sequestering 1/5 of human carbon output. Whereas if you grew bamboo, you'd cover the contiguous US for the same output.
Do I believe them? No. But even 10x worse is cheap enough to change the world.