Sorry for everything that has happened up to this point and I hope your wife begins to feel better soon.
As far as Royal's position it does appear they should work on their wording which appears to suggest you should board with whatever possible infection may be present as long as it isn't "COVID-19". There has to be a better way to handle this scenario independent of the financial impact of no refund/no FCC which clearly they should not be expected to provide.
Perhaps they are hesitant to state you shouldn't board as that implies they are instructing you not to cruise which could have implications in a legal or financial sense. For example if they "deny" you boarding (by telling you not to board) then a credit card company could look at that as if Royal failed as a merchant to provide the service you purchased.
Disney charges outrageous prices so they can bury losses and still be profitable. As a company that is their prerogative to take this approach. That doesn't mean every other company on the planet should follow the Disney way.
As a consumer I don't want to overpay for my purchases so that others can not follow policy. I feel terrible for everything your family is going through but I don't think Royal should deviate from their policy and grant you a refund or FCC. I state this as I myself will probably walk away from a cruise in a week knowing all I'll get back is port fees and taxes. My personal situation has changed since I booked this cruise and now with a week to go I accept that's on me. No refund, no FCC, no attempt will be made to lie or fake a false positive or any other means to weasel a refund. At this point unless there is a pop up hurricane induced refund option I will lose my money and I accept that is on me.