It's not that surprising. Both MIA and FLL are now outside of the "cone" for the storm. PBI is inside, but not by much.
Here's the current map (as of the 5am update on 8/1/20). The cone is between the blue lines. I included the "Most Likely Arrival Time of Tropical Storm Force Winds" as an overlay. Those are the black lines with the dates and times.
Source:
https://www.nhc.noaa.gov/
I'm fairly certain that all airports shut down once they reach Tropical Storm Force Winds (39 miles per hour). As you can see, none of the South Florida airports will reach that stage until after 8pm tonight.
I'm in Fort Lauderdale. Right now, it looks to be a nice morning. Some patchy clouds and no wind.