Would U.S. neutrality patrols have confronted a concentrated German surface force?

Would the United States have intervened if Lütjens's concentrated force attacked neutral or American shipping in the western Atlantic?

Possibly, but direct action against four capital ships would be a major escalation and much harder to justify or execute than enforcing the established American position against submarine attacks.

American cruisers and battleships could patrol the western Atlantic and attempt to intervene against a German sortie. Confronting all four German capital ships would be a much more difficult commitment. Intervention could immediately start a war. The prospect of patrols therefore did not establish that American ships would attack the concentrated force.