That article’s only real point is that we shouldn’t pin our hopes entirely on sequestration. Nothing about it being invalid or “a scam.”

Basically summed up in these two paragraphs:

On the one hand, putting more money into carbon removal will help scale up—and drive down the cost of—technologies that will be needed in the future.

On the other hand, the growing excitement around these technologies could feed unrealistic expectations about how much we can rely on carbon removal, and thus how much nations and corporations can carry on emitting over the crucial coming decades. Market demands are also likely to steer attention toward cheaper solutions that are not as reliable or long-lasting.

Carbon sequestration is likely to play a part in becoming carbon negative, and deserves to be explored.