Trump has de-institutionalised the US presidency. He is a bizarrely post-modern but powerful emanation of the great man theory of history.
The last thing a US president wants is to tell a friendly country what it should do.
Thus the real question about electability is not who seems like the safest bet to voters in the middle. It is who can excite the voters who gave the benefits of their grave doubts to two very unusual, indeed unprecedented, candidates: Obama and Trump.
Trade wars do direct economic damage. Contrary to what Trump has claimed, they increase prices for US consumers and for businesses buying intermediate goods.