Even in conventional English, “Non-stop” doesn’t necessarily mean without stopping at all. The express train from New Haven to Grand Central, for example, is called express because it doesn’t stop between Connecticut and New York City, though there are several stops in Connecticut and one stop in Harlem.
“Non-stop” in context could just mean that they were not stopping in any towns they passed.
Even in conventional English, “Non-stop” doesn’t necessarily mean without stopping at all. The express train from New Haven to Grand Central, for example, is called express because it doesn’t stop between Connecticut and New York City, though there are several stops in Connecticut and one stop in Harlem.
“Non-stop” in context could just mean that they were not stopping in any towns they passed.