In order to blame the bad actions of the United States for the "polycrisis", you really need to excuse all of the bad actions of everyone else.
To pick a timely issue : blaming the USA for the actions of Israel in their* Gaza territory we would need to excuse Israel for the actions of Israel.
If a general strike would have any effect id support it, but the target should be the specific actions of our country rather than the actions of other sovereign nations.
(*: If the govt of israel does not recognize a distinct Palestinian state, and the pseudo-governments of Palestine cannot exert sovereign control to keep Israel out, then Palestine is [unjustly] and [occupied] territory of Israel.)
In common commercial english, i would read that as "this merchant will offer to trade any of the books for an amoumt of currency equal to half the book's cover price plus $1."
Such vagueness also suggests sufficient informality that the merchant may either accept seperate offers or veto the general rule on a case-by-case basis.