Sorry, this guy should quit and find another job.
Assembling a car is unskilled labor. Unionization just drives the cost of production up. If the work is to hard, then quit.
Is framing a house, pouring/finishing concrete or laying brick/tile ergonomic? People do it every day in bad weather.
Unions served a purpose when workers were exploited. There was a large pool of unskilled workers, and if one got hurt, you just got another one because the job required little skill. But the unions also artificially inflated wages for many of these jobs. OSHA and many local and federal laws now exist to protect workers that didn't exist many years ago.
All this guy is doing is highlighting why a company will eventually get rid of his job an use a robot to do the same repetitive task.