It isn't that the process takes two years - I'm guessing they were talking more about being a good career move for a CEO candidate:
A great CEO has many options in front of them of what to do with their career. Asking them to take on a company that doesn't have much runway limits the time they have to get in, become the new leader, and mold the organization. Therefore, it is not likely to be their best option, which means the candidates who are interested are more likely to be not-so-great CEO candidates.
The process of finding a 'good fit' CEO could very well take a very long time though. But your point is valid as well - nobody wants to jump onto a ship that's about to go down.
A great CEO has many options in front of them of what to do with their career. Asking them to take on a company that doesn't have much runway limits the time they have to get in, become the new leader, and mold the organization. Therefore, it is not likely to be their best option, which means the candidates who are interested are more likely to be not-so-great CEO candidates.