Why armed blockade-running would make America the aggressor

Could the United States challenge the blockade by escorting cargo to neutral Holland or Norway?

It could trade with neutral ports, but that would not break the blockade; forcing an escorted convoy through to Germany would make the United States the active belligerent.

The scenario becomes credible only if American merchant shipping is backed by the fleet and deliberately challenges a wartime blockade. That act would make the United States the escalator rather than the victim of an unprovoked British attack. Slow American battleships would enter an active war zone against Britain and France already short of fuel. Trade with neutral ports such as the Netherlands or Norway is not equivalent to forcing a convoy into Germany. Britain could permit neutral trade while purchasing suspect cargoes at slightly above-market prices, whereas a fleet trying to break the blockade would have to confront it directly.