The last line doesn't follow at all. Science can discover how priming works, including how it stops working.
Something similar goes for phrenology (the prediction of mental attributes from head shape): Science can discover where phrenology works and which traits it can predict and where it stops working. The sheer number of possible traits and populations one can correlate makes me confident you'd find something scientific if you looked. But if science discovers that elongated heads predict high extraversion among Swedes, and is otherwise largely wrong or unpredictive, would you say that phrenology is science?
Steven Kaas quipped something I find applicable: "...
Related to: Power of Suggestion
He then comments on and extensively quotes the Higher Education piece Power of Suggestion by Tom Bartlett, which I linked to at the start of my post. I'm skipping that to jump to the novel part part of Steve's post.
Interesting hypothesis.