I read the article and the method of sequestration they have been using is extremely limited, it's main benefit being minimal long term sequestration by some leafy build up. Even their timber cultivation is a lacklustre effort as timber is often burnt after its limited lifespan. Burning the place down was likely the best thing that could have happened for their long term sequestration goals (sequestration in the form of charcoal). Long term sequestration is best done in the form of hummus, with cellulose and lignin as the carbon holding elements. I don't know where they get the "carbon saturation". Optimum carbon is a 1:7 carbon soil ratio, so over that area we are talking about millions of tons which is not something they could have achieved.

The idea that animal protein as a food source is not viable is largely a correct one however there are significant portions of the earth's landmass that are unsuitable for commercial cultivation. In these places animal grazing is still the best means of calorie extraction from these regions.

The CSIRO among other organisations have long been investigating macroalgal solutions to in rumen methenogenesis. Possibly reducing green house gas emissions from cattle to between 85-99%. That is to say as little as 2 grams of a seaweed cultivar could solve the methane problem, in conjunction with sound diet practices. The linked article (within the linked article) talks about "lacklustre reduction" but utterly ignores other studies achieving 99%. A minute of googling shows achievable results possible on a commercial scale.

The idea of decreasing the time to market of these animals is the opposite of what is needed, it is the grossly intensive feeding regimens of the cattle industry that causes excess methenogenesis. Excess protein causes methanogenesis.

Biological nutrient cycling allowing there is a world of global warming negative (carbon sequestering) beef/dairy in the not too distant future.

For a number of reasons these methods are unlikely to be embraced by the beef/dairy industries as they require mass silviculture which is largely incompatible with current practices.

As usual commercial industry is barking up the wrong tree, trying to amend their inherently flawed method rather than begin a new less intensive, sustainable method.

With that said there is a debate to be had about the phasing out of animals proteins as food to benefit human health but the b12 problem has to be overcome.