The article uses the premise that we have 15 years to avert a runaway crisis - and points out that nuclear won't be able to scale by then.

That second part is entirely true. But most people don't actually think the world will stop existing then even if a few points are knocked off of GDP. Clean energy production will still be important 50 years from now.

I think you misunderstood. If the goal is to prevent climate catastrophe, there isn’t really a solution. Mitigation of the worst of it might be possible, but anyone reading the linked article wouldn’t take that as the central thesis.