This is seriously outrageous. There is little or no regulation of on-board casino operations as far as I can tell. Most major cruise lines are members of the Cruise Line Industry Association, which has a gambling "policy" (https://www.cruising.org/about-the-i...other/gambling), but it is only vaguely stated and of dubious enforcability. However, it does state that the Cruise Vessel's equipment will meet the regulatory standards of the Nevada Gaming Control Board "for payback and internal software." I am sure if I dug through those regs, I can find something about how a progressive machine cannot just be "reset" as it will manually alter the payback for the machine.
Seems like if you're not getting satisfaction on this from the Hotel Manager, it's worth it to write to the cruise line's main office and complain (be sure to send a copy to the cruise line's general counsel) and, failing that, send a letter to an industry publication about what you observed and the Cruise Line's failure to address the issue.