We are living in a strange world where Tesla has a higher market cap than GM. There has been a stall in new car sales globally, especially in China where sales declined. He thinks all the parts manufacturers will suffer to a degree. Magna will be a survivor and will make the transition into electric cars going forward. He would not hesitate to own it for the long term. He does not own it presently.
Why the selloff today? Teck may be expanding its deal with a competitor causing a sizable share price sell off (over 10% today) -- this may double Teck's capacity. People may also be concerned about future coal demand and exports. There just not seem to be any catalysts to spark his interest. It is not wise to panic on this, there will be time for recovery to allow you to assess the situation.