If Donald Trump recited “The Star-Spangled Banner” before a baseball game, it would be criticized as an alt-right dog whistle. So naturally spring-loaded opinions rained down in Poland after he delivered a defense of Western values.

Only this particular American president could say, “Let us all fight like the Poles—for family, for freedom, for country, and for God,” and elicit attacks from the left as sending subliminal messages to his isolated rural supporters, and from the anti-Trump right as a fake speech because he gave...