My guess is that JetBlue won't split the ticket overnight at MCO because they don't offer flights with connections greater than 4 hours. At least they haven't in the past and I've not seen any indication that policy has changed.

The only other airline they have an agreement with where they could interline you to would be AA. And I wouldn't bet on that happening.

Unfortunately a 2 hour schedule change isn't a "major" change for most airlines. I'm guessing they'll be somewhat flexible with you if you have an option that makes sense, but the ultimate recourse you probably have is simply a refund of the ticket.

I know it is frustrating, but having a non-refundable booking 2 hours after landing is somewhat risky no matter how you look at it. What if there are flight delays. Or long lines at immigration? Or a secondary screening at customs?

That's not to say that JetBlue shouldn't work with you a bit, but their responsibility is really only to get you safely to MBJ airport, not to handle the ground tours, too.