If the entire world's electric supply isn't decarbonised at that point then that money would be better spent on deploying renewables somewhere without a 100% clean grid as the article says or electrifying heat or industry.
That has issues with proving the deployment actually displaces carbon but carbon capture has similar issues proving that the carbon is actually permanently removed.
That's the thing. All of these mitigations are meaningless if we still have vast industries predicated on burning fossil carbon.
And once we've eliminated the burning of fossil carbon, the mitigations are unnecessary. Nature will gradually find an equilibrium, and anything we do to speed it up (even removing carbon) is as likely to cause harm as good.
Maybe there is a future where we have so much extra renewables that we can think about trying to undo what we've done. But any effort spent on it now feels like an attempt to decrease the need to eliminate fossil fuels as fast as possible.
That has issues with proving the deployment actually displaces carbon but carbon capture has similar issues proving that the carbon is actually permanently removed.