The reason that pointing out automation and not trade is the core reasons for decline in manufacturing helps us understand the underlying cause, which points to the real solution.
If automation and technology is the real cause of disruption, that points to the need for helping workers retool and re-skill for the new opportunities that are created.
Every day many jobs are destroyed and created — that is the nature of a capitalist economy due to supply and demand. The real solution is to help people navigate this dynamic climate better.
Furthermore, whether massive technology or trade will destroy all jobs and leave people unoccupied itself is not super clear. There are so many jobs available today, but they are not the jobs of yesterday (more service oriented, in healthcare, education, etc). So again the problem is not massive unemployment, it is helping people deal with structural changes to the economy and making local areas more resilient to this disruption through a mix of social policy and smart market oriented reforms.