I think as far as SXM is concerned, if you have three shots, or J & J plus a booster, they don't care how far apart they were.

As far as SXM changing rules, they have changed things too often, with too little notice, to allow people to plan. Very like when they shut down in March last year, with absolutely NO concern for tourists who had to scramble to try to get back home. I wouldn't presume to speak for JD, but that has to really stick in anyone's craw, that had to scramble, just to try to get home.