I’m not sure why there would be some upper limit on what we could remove. The only real limiting factor is cost… but if these technologies are also producing valuable materials like carbon nanotubes in an industrially useful form, then there’s little limit on how much you could capture.
Also, note an important part of that “gigatons” statement from your article:
The EASAC, which advises European policymakers, said these technologies have “limited realistic potential to remove carbon from the atmosphere” and not at the scale in some climate forecasts, such as several gigatons of carbon each year after 2050.
After 2050. That’s a ways out. Just because our carbon capture potential technology doesn’t exist at the level required to do the work yet doesn’t mean that it won’t develop to that level in the next 32 years. 32 years is a long freaking time in terms of technology development.
I suspect that such a thing would have extremely limited impact on the overall footprint of humanity. Certainly not enough to get the job done.
Ultimately, you’re talking about taxing energy itself, which amounts to a tax on… doing anything in the economy. It could help shift us to less carbon based energy, but it won’t get the job done on its own, and for the foreseeable future, the only real alternative is nuclear power, which tends to get massive pushback from the same people who are pushing to deal with climate change.