Not sure your logic exactly works here, although I think their...

Not sure your logic exactly works here, although I think their mathematics are out based on what is reported. They state that hemp sequesters 150% of it's mass in CO2. With all things remaining equal, and not accounting for production of Hemp Black Ink and CO2 production as part of this, then one could imagine 1kg of ink removing 1.5kg of CO2. But yes, 5kg does not seem to fit.

And you're totally right, where is the emphasis in all of these blog posts on anything related to Hemp Black? Keep calling it what it is dammit!